Applied Surface Science (v.258, #24)
Synthesis and characterization of YSZ by spray pyrolysis technique by L.D. Jadhav; A.P. Jamale; S.R. Bharadwaj; Salil Varma; C.H. Bhosale (9501-9504).
► The YSZ thin film has been successfully deposited at 400 °C. ► Deposition at 400 °C significantly limits the growth mechanism along (1 0 1). ► The enhancement in conductivity exhibits the YSZ as a thin solid electrolyte.The conventional zirconium based yttria stabilized zirconia (YSZ) electrolyte has been synthesized from aqueous solution by cost effective air atomized spray pyrolysis technique (SPT). The films show well developed dense, nanocrystalline material. The thermal analysis of zirconyl nitrate reveals the possibility of crystalline YSZ film formation only above 400 °C, which is confirmed from the XRD pattern. The activation energy of 1.14 eV clarifies its conductivity behavior, verified from DC and AC conductivity measurements.
Keywords: DC conductivity; Thin films; XRD;
Preparation of thermo-responsive superhydrophobic TiO2/poly(N-isopropylacrylamide) microspheres by Hao Chen; Shuaijun Pan; Yuzi Xiong; Chang Peng; Xiangzhong Pang; Ling Li; Yuanqin Xiong; Weijian Xu (9505-9509).
► The thermo-responsive superhydrophobic microspheres are obtained via a process that combines sol-gel method and ATRP. ► The reversible switch between hydrophilicity and superhydrophobicity of TiO2/PNIPAM composites is rapid and significant. ► The as-prepared composites offer us an opportunity to develop cost-effective smart materials.Here we reported a facile method that combined sol–gel and surface-initiated atom transfer radical polymerization (ATRP) to prepare thermo-responsive superhydrophobic TiO2/poly(N-isopropylacrylamide) microspheres with core–shell structure. The surface coated with microspheres show hydrophilic properties (CA = 90.5 ± 2.3°) at 27 °C, it changes to superhydrophobicity (CA = 150.2 ± 2.3°) while the temperature rises up to 42 °C. This performance is attributed to lower critical solution temperature (LCST) phenomenon of Poly (N-isopropylacrylamide). Five cycle measurements of water droplet reversible switch between hydrophilicity and superhydrophobicity were demonstrated temperature-responsive surface property. The changes were rapid and significant. The as-prepared particles have been characterized by scanning electron microscopy, transmission electron microscopy, thermal gravimetric analysis, FT-IR analysis, and dynamic light scattering.
Keywords: Thermo-responsive; Superhydrophobic; Core–shell structure;
Deposition, characterization and optimization of zinc oxide thin film for piezoelectric cantilevers by Peihong Wang; Hejun Du; Shengnan Shen; Mingsheng Zhang; Bo Liu (9510-9517).
► Various ZnO films with preferred ZnO(0 0 2) orientation were deposited at room temperature. ► The influence of different deposition conditions on the crystalline quality and microstructure of ZnO film were investigated. ► The ZnO film based piezoelectric micro cantilever was fabricated and its dynamic performance was measured. ► The d 31 of ZnO film deposited under best sputtering condition is −3.21 pC/N.In this work, piezoelectric zinc oxide (ZnO) thin films are deposited under different deposition conditions using RF magnetron sputtering method. The influence of RF power, O2/(Ar + O2) gas ratio and sputtering pressure on the deposition rate, crystalline structures, surface roughness and composition purity of ZnO film are investigated by X-ray Diffractometer (XRD), scanning electron microscopy (SEM), atom force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDS). All the fabricated ZnO films have a preferred ZnO(0 0 2) orientation. When the gas ratio of O2/(Ar + O2) is 25% and the working pressure is 0.8 Pa, the grain size in the ZnO thin film is of the largest and the ZnO film has a very smooth and dense surface. The SEM cross-sectional image of the ZnO film confirms that the ZnO thin film has a columnar structure and the c-axis is perpendicular to the substrate surface. The EDS analysis shows the ZnO film has only Zn and O elements. Different ZnO film based piezoelectric micro cantilevers are fabricated using micromachining techniques and the dynamic response of these piezoelectric cantilevers are measured by laser Doppler vibrometer (LDV). The tested results from LDV show that the deflection of the piezoelectric cantilever is linear with the driving voltage. The transverse piezoelectric constant d 31 of the ZnO thin film deposited under best conditions is calculated as −3.21 pC/N by the LDV data. This value is higher than other published works. In future, these ZnO thin films will be used in our ongoing project for the design, simulation and fabrication of smart slider with a built-in ZnO sensor/actuator in the hard disk drives.
Keywords: Zinc oxide film; RF magnetron sputtering; Deposition condition; Optimization; Piezoelectric cantilever; Transverse piezoelectric constant;
Specific interactions of functionalised gold surfaces with ammonium perchlorate or starch; towards a chemical cartography of their mixture by D. Mercier; C. Mercader; S. Quere; L. Hairault; C. Méthivier; C.M. Pradier (9518-9525).
► Measurements of interactions by Quartz Crystal Microbalance. ► AFM and CFM measurements, tip functionalisation. ► Surface nano-imaging.By functionalising gold samples, planar wafers or AFM tips, with an acid- or an amino acid-terminated thiols, mercaptoundecanoic acid (MUA) and homocystein (H-Cyst) respectively, we were able to differentiate the interactions with ammonium perchlorate (AP) and starch (S), two components of a nanocomposition mixture.To do so, the interaction between gold functionalized surfaces and the two targeted compounds have been characterized and quantified by several complementary techniques. Polarisation modulation-infrared spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS), providing chemical analyses of gold surfaces after contacting S or AP, proved that both compounds were retained on MUA or H-Cyst-modified surfaces, but to various extents. Quartz crystal microbalance on-line measurements enabled to monitor the kinetics of interaction and showed distinct differences in the behaviour of MUA and H-Cyst-surfaces towards the two compounds.Having observed that only H-Cyst-modified surfaces enables to get a contrast on the chemical force microscopy (CFM) images, this new result could be well explained by examining the data obtained by combining the above-mentioned surface characterisation techniques.
Keywords: QCM; PM-IRRAS; Gold functionalisation; Chemical force microscopy;
Detailed evaluation of protein adsorption on alumina surface through surface plasmon resonance phenomenon by Hiroki Akasaka; Miyuki Konishi; Naoki Gawazawa; Shigeo Ohshio; Ikumi Toda; Hidetoshi Saitoh (9526-9530).
► Alumina films were studied in terms of their initial protein adsorption through the SPR to investigate the adsorption of HSA. ► Na2HPO4·12H2O, NaH2PO4·2H2O and deionized water were mixed to coordinate the PB. ► The observed SPR angle behavior indicated that HSA was immediately adsorbed on alumina films. ► The adsorbed HSA was desorbed by the etching of the alumina layer. ► Thus, HSA cannot remain adsorbed on an alumina layer for a long time.To investigate the adsorption of human serum albumin (HSA) on alumina, alumina films were studied in terms of their initial protein adsorption through the surface plasmon resonance (SPR) phenomenon using a multilayer device consisting of an alumina layer on Au. HSA in a phosphor buffer (PB) was used as a protein. Na2HPO4·12H2O, NaH2PO4·2H2O, and deionized water were mixed to coordinate the PB. From the attenuation of reflected light, the SPR angle was determined as the angle with minimum reflection intensity. The observed behavior of the SPR angle indicated that HSA cannot remain adsorbed on alumina for a long time. To understand this phenomenon, the etching rates of PB solutions were estimated, and were −3.44, −2.64, and −0.41 nm/h for 0.5, 0.3, 0.1 M solutions, respectively. Upon evaluating the adsorption of HSA, the observed SPR angle behavior indicated that HSA was immediately adsorbed on alumina films. After that, the adsorbed HSA was desorbed by the etching of the alumina layer. Hence, these results also indicated that HSA cannot remain adsorbed on an alumina layer for a long time.
Keywords: Alumina; Human serum albumin; Surface plasmon resonance; Multilayer SPR device; Etching;
Experimental study on friction and wear behaviour of amorphous carbon coatings for mechanical seals in cryogenic environment by Jianlei Wang; Qian Jia; Xiaoyang Yuan; Shaopeng Wang (9531-9535).
► The coefficient of friction of a-C coatings was in the range of 0.10 to 0.15 under cryogenic environment. ► The coatings had a graphite-like characteristic and were available to cryogenic environments. ► The deposition of the a-C coatings could significantly reduce the specific wear rate of seal rings. ► We explore the suitability of a-C coatings used in cryogenic mechanical seal.The service life and the reliability of contact mechanical seal are directly affected by the wear of seal pairs (rotor vs. stator), especially under the cryogenic environment in liquid rocket engine turbopumps. Because of the lower friction and wear rate, amorphous carbon (a-C) coatings are the promising protective coatings of the seal pairs for contact mechanical seal. In this paper, a-C coatings were deposited on 9Cr18 by pulsed DC magnetron sputtering. The tribological performances of the specimen were tested under three sealed fluid conditions (air, water and liquid nitrogen). The results show that the coatings could endure the cryogenic temperature while the friction coefficients decrease with the increased contact load. Under the same contact condition, the friction coefficient of the a-C coatings in liquid nitrogen is higher than that in water and that they are in air. The friction coefficients of the a-C coatings in liquid nitrogen range from 0.10 to 0.15. In the cryogenic environment, the coatings remain their low specific wear rates (0.9 × 10−6 to 1.8 × 10−6 mm3 N−1 m−1). The results provide an important reference for designing a water lubricated bearing or a contact mechanical seal under the cryogenic environment that is both reliable and has longevity.
Keywords: Amorphous carbon; Mechanical seal; Cryogenic; Friction; Wear;
Ab initio investigation of the SCN− chemisorption of single-walled boron nitride nanotubes by Alireza Soltani; Nasim Ahmadian; Yaser Kanani; Aliakbar Dehnokhalaji; Hossein Mighani (9536-9543).
► We explored the adsorption behavior of the SCN− on outer surface BNNTs via DFT. ► We reported the NBO charge distribution of SCN− on BNNTs surface. ► Chemisorptions are observed for SCN− on Al- and Ga-doped BNNTs. ► Notable changes are observed in the electronic properties of BNNT after doping.The thiocyanate anion (SCN−) adsorption capacity of zigzag single-walled boron nitride nanotubes (SWBNNTs) is studied via first-principles theory. Binding energy corresponding to the most stable configuration of SCN−/BNNT is found to be −148.42 kJ mol−1, which is typical for the chemisorptions. Our results indicate that both aluminum and gallium doping can significantly enhance the adsorption energy of SCN−/BNNTs complexes. Our electronic results reveal that there is a significant orbital hybridization between two species in adsorption process being an evidence of strong interaction. Thus, we arrive at the prediction that the BNNTs nanocage can be implemented as suitable sensor for practical applications.
Keywords: Adsorption; BNNT; SCN−; Chemisorption; Quantum molecular descriptors;
Characterization of amorphous Co–P alloy coatings electrodeposited with pulse current using gluconate bath by Parthasarathi Bera; H. Seenivasan; K.S. Rajam; V.K. William Grips (9544-9553).
► Co–P alloys are electrodeposited with pulse current using gluconate bath. ► Alloy coatings are amorphous in nature with different P contents. ► As-deposited alloys consist of Co0, Co2+ and P δ−, P5+ species. ► Increase in the amounts of Co0 and P δ− is observed upon intermittent sputtering. ► Heat treated coatings show average microhardness values of 940 HK.Co–P alloy coatings were electrodeposited with pulse current using gluconate bath and characterized by XRD, FESEM, AFM, DSC and XPS. Co–P alloy coatings are amorphous in nature as demonstrated by XRD. FESEM exhibits the “cauliflower type” morphology that is distinctive of nanocrystalline metals and alloys. Co–P alloys are found to follow instantaneous growth mechanism as revealed by AFM studies. Two exothermic peaks at 320 and 340 °C in DSC profiles of Co–P deposit correspond to the crystallization of the deposit. Detailed XPS studies of these alloy coatings have shown that as-deposited coatings consist of Co metal as well as oxidized Co species. P has mostly been present as bulk alloy on the surface as P δ− form. Increase in the amounts of Co metal and P δ− are observed upon intermittent sputtering. No appreciable increase in microhardness is observed with increase in the phosphorous content, but it increases with heat treatment significantly.
Keywords: Co–P alloy coatings; Electrodeposition; Pulse current; Gluconate bath; XPS;
Gas sensing properties of p-type semiconducting vanadium oxide nanotubes by Minglang Yu; Xueqin Liu; Yuan Wang; Youbin Zheng; Jiawang Zhang; Mingyang Li; Wei Lan; Qing Su (9554-9558).
► The vanadium oxide nanotubes are superior sensitive and stable to ethanol vapor and NO2. ► The vanadium oxide nanotubes are of p-type behavior at 80 °C. ► The vanadium oxide nanotubes are of p-type behavior at 260 °C.Vanadium oxide nanotubes (VONTs) were synthesized using the V2O5 powder as precursor with dodecylamine as structure-directing template via one-step hydrothermal way. The prepared VONTs sensors exhibit excellent sensing sensitivity and superior recovery property in detecting ethanol vapor. The response to the ethanol vapor and NO2 gases confirms that the samples are of p-type behavior at 80 °C, which is associated with the presence of the protonated amine molecules in the VONTs. The sample changes to n-type behavior at 260 °C arising from the decomposition of the protonated amine molecules. The p-type VONTs have potential for development of a novel gas sensor.
Keywords: Nanotubes; Vanadium oxide; P-type semiconductor; Sensors;
Surface mechanical properties of S30432 austenitic steel after shot peening by K. Zhan; C.H. Jiang; V. Ji (9559-9563).
► The surface yield strength of S30432 austenite steel after conventional and dual shot peening has been investigated by X-ray stress analysis method. ► Both shot peening treatment could greatly improve the surface yield strength. ► The improved yield strength is then discussed in terms of microstructure in the deformed layer. ► Refined domain size and high micro-strain and high density of dislocation are induced in the deformed layer.The surface yield strength of S30432 austenitic steel after conventional and dual shot peening treatments has been investigated by means of X-ray stress analysis. The results showed that the proof stress σ 0.2 of the shot peened surface increased to around 830 MPa and 940 MPa after conventional and dual shot peening, respectively. While for the bulk S30432 austenitic steel, the yield strength was 268 MPa. The strengthen mechanism was discussed in terms of microstructure by X-ray line profile analysis method. The results revealed that the refined domain size and high micro-strain were induced in the deformed surface layer. This changed microstructure was mainly responsible for the high yield strength of shot peened surface. The surface yield strength of the material surface can be obtained from the proposed X-ray stress analysis method. Therefore, this method can be considered as a complementary approach in investigating the microstructural hardening effect of SP treatment.
Keywords: Surface yield strength; Shot peening; Microstructure;
Study of plasma immersion ion implantation into silicon substrate using magnetic mirror geometry by E.J.D.M. Pillaca; M. Ueda; K.G. Kostov; H. Reuther (9564-9569).
► Plasma density increases in magnetic bottle configuration due to magnetized electrons drifting in crossed E × B fields, promoting electronneutral collision and as a result, the ion current density increases. ► Plasma immersion ion implantation in crossed E × B fields provides significant changes in surface properties of the samples. ► The plasma immersion ion implantation process with magnetic field has increased the dose and the depth of implantation by a factor of 1.5 in the case of sample implanted at high energy.The effect of magnetic field enhanced plasma immersion ion implantation (PIII) in silicon substrate has been investigated at low and high pulsed bias voltages. The magnetic field in magnetic bottle configuration was generated by two magnetic coils installed outside the vacuum chamber. The presence of both, electric and magnetic field in PIII creates a system of crossed E × B fields, promoting plasma rotation around the target. The magnetized electrons drifting in crossed E × B fields provide electron-neutral collision. Consequently, the efficient background gas ionization augments the plasma density around the target where a magnetic confinement is achieved. As a result, the ion current density increases, promoting changes in the samples surface properties, especially in the surface roughness and wettability and also an increase of implantation dose and depth.
Keywords: Plasma immersion ion implantation with magnetic field; Silicon; Magnetic mirror geometry; Crossed E × B fields;
Poly(vinylidene fluoride) reinforced by carbon fibers: Structural parameters of fibers and fiber-polymer adhesion by Jianghong Wang; Defeng Wu; Xiang Li; Ming Zhang; Weidong Zhou (9570-9578).
► CF reinforces PVDF evidently especially after surface treatment. ► Nielsen model can be well used to describe the concentration effect of CF. ► Theoretical orientation degree value of CF agrees with the experimental one.Poly(vinylidene fluoride) (PVDF) composites containing carbon fibers (CFs) with or without surface treatment were prepared via melt mixing. The mechanical properties of the PVDF/CF composites were then studied to explore the relations between the short-range and long-range structures of CFs and the properties of the composites. The results showed that the presence of CFs had a reinforcement effect on the PVDF and the Nielsen model was used to describe the concentration effect of CFs, especially at the lower concentration levels. The short-range aspect ratio structure and the long-range orientation structure of the CFs are the two most important structures that affected the final properties of the composites. The effective aspect ratio and orientation degree of the CFs in the PVDF matrix can be evaluated by the Halpin-Tsai and the Krenchel-COX models, which agree well with the experimental observations. After surface treatment, the CFs show stronger reinforcement effect due to reduced interfacial tension and increased interfacial area between two phases
Keywords: Poly(vinylidene fluoride); Carbon fiber; Composites; Structural parameters; Interfacial tension;
Si nanoripples: A growth dynamical study by Prabhjeet Kaur Dhillon; Subhendu Sarkar; Alexis Franquet; Alain Moussa; Wilfried Vandervorst (9579-9583).
► Si (0 0 1) surface was sputtered with low energy oxygen beam. ► Secondary ion signals were detected. ► Temporal study of the resulting morphology shows two distinct growth regimes. ► The onset of ripple formation is obtained from dynamic scaling studies of the surface.Si(1 0 0) surface was physically eroded using 1 keV O 2 + ion beam and the resultant surface was studied by atomic force microscopy (AFM). The data were analyzed within the framework of dynamic scaling theory. Results indicate two growth regimes during the evolution of ripples on the surface. The first growth regime which is an unstable one continues for around 35 min and has an exponential growth exponent. The second growth regime on the other hand sets in after this time and exhibits a growth exponent of 0.38. However, for the entire bombarding period a single coarsening exponent (1/z = 0.44) extracted from the power spectral density peak widths of the acquired AFM images is observed. The ripple amplitudes however show an exponential increase over the time domain studied in agreement with the Bradley–Harper theory. Finally, roughness measurements clearly indicate transition regions of sputter yield variations and the onset of ripple formation.
Keywords: Sputtering; Nanopatterning; Atomic force microscopy; Scaling;
Size controlled synthesis and photocatalytic activity of anatase TiO2 hollow microspheres by Charu Dwivedi; V. Dutta (9584-9588).
► A time consuming and one step approach of synthesizing hollow microspheres. ► The role of precursor concentration and applied voltage has been investigated. ► Particle size effect on band gap.Titanium oxide hollow microspheres were synthesized from organic precursor titanium tetraisopropoxide (TTIP) using continuous spray pyrolysis reactor. Effects of precursor concentration, applied voltage and annealing have been investigated. It was observed that the annealing of the as-synthesized TiO2 hollow microspheres at 250 °C, which had an average external diameter of 200 nm, leads to an increase in the size and also more spherical shape. The precursor concentration and applied voltage were found to have a direct impact on the size of the microspheres, which is also evident in the absorption spectrum. The as-prepared TiO2 hollow microspheres exhibited good photocatalytic activity for the degradation of MO.
Keywords: TiO2 hollow microspheres; Spray pyrolysis; Electric field; Microscopy; Microstructures;
XPS analyses of Ta/MgO x /Ni81Fe19/MgO x /Ta films by Minghua Li; Gang Han; Yang Liu; Chun Feng; Haicheng Wang; Jiao Teng; Guanghua Yu (9589-9592).
► Ta/MgO x /Ni81Fe19/MgO x /Ta films were prepared by magnetron sputtering. The anisotropic magnetoresistance (AMR) increases dramatically after annealing. ► The chemical states of Ta and MgO x at the interface of the NiFe/MgO x /Ta films, which were prepared at the different technological conditions, were analyzed by X-ray photoelectron spectroscopy (XPS). ► The AMR of Ta/MgO x /Ni81Fe19/MgO x /Ta films is related to the chemical states of MgO x . These states were produced under different technical conditions and influence the film properties.Ta/MgO x /Ni81Fe19/MgO x /Ta films were prepared by magnetron sputtering. The anisotropic magnetoresistance (AMR) increases dramatically after annealing. The chemical states of Ta and MgO x at the interface of the NiFe/MgO x /Ta films, which were prepared at the different technological conditions, were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that the AMR of the films is related to the chemical states of MgO x . The chemical states of Mg are different when MgO x is prepared at different technological conditions. Therefore, increasing the AMR is beneficial when more Mg2+ ions are present in the MgO x films.
Keywords: Magnetic films; X-ray photoelectron spectroscopy; MgO x ;
Preparation of TiO2 nanotubes coated on polyurethane and study of their photocatalytic activity by Pei Liu; Haijin Liu; Guoguang Liu; Kun Yao; Wenying Lv (9593-9598).
► TiO2 nanotubes have been synthesized by a hydrothermal method. ► The surface of TiO2 has been effectively modified with silane coupling agents. ► TiO2 nanotubes–polyurethane photocatalytic composite have been synthesized through a series of activation reactions using polyurethane (PU) membrane as a solid carrier. ► The new composite exhibit very good photocatalytic activity and are recyclable.TiO2 nanotubes have been synthesized by a hydrothermal method and their surface has been effectively modified with silane coupling agents. TiO2 nanotubes–polyurethane photocatalytic composites were then successfully synthesized through a series of activation reactions using polyurethane (PU) membrane as a solid carrier. All of these products have been characterized and identified by means of scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The results have shown that the TiO2 nanotubes treated by silicon alkylation could efficiently combine with the solid carrier (PU) and that the surface multilayer structure was very stable and compact. In addition, the new composite showed very good photocatalytic activity and was recyclable, which was demonstrated by the photocatalytic degradation of Rhodamine B.
Keywords: TiO2 nanotube; Silane coupling agents; Polyurethane membrane; Photocatalysis;
Sn whiskers removed by energy photo flashing by N. Jiang; M. Yang; J. Novak; P. Igor; M. Osterman (9599-9603).
► Sn whiskers were sintered by intense light flashing (Photosintering). ► Photosintering can effectively eliminate Sn whiskers. ► Photosintering would not damage electronic devices. ► Photosintering is a very promising approach to improve Sn-based electronic surface termination.Sn whiskers have been known to be the major issue resulting in electronic circuit shorts. In this study, we present a novel energy photo flashing approach (photosintering) to shorten and eliminate Sn whiskers. It has been found that photosintering is very effective to modify and remove Sn whiskers; only a sub-millisecond duration photosintering can amazingly get rid of over 90 vol.% of Sn whiskers. Moreover, this photosintering approach has also been proved to cause no damages to electronic devices, suggesting it is a potentially promising way to improve Sn-based electronic surface termination.
Keywords: Sn whiskers; Sintering; Light flashing; Whisker elimination; Surface finish;
Effects of annealing temperature on ZnO and AZO films prepared by sol–gel technique by Zi-Neng Ng; Kah-Yoong Chan; Thanaporn Tohsophon (9604-9609).
► Low cost sol–gel spin coating technique was used to fabricate the ZnO films. ► Influences of annealing temperature on the structural and optical properties of the ZnO and AZO films were investigated. ► The experimental results reveal that the annealing treatment affects the structural and optical properties of the ZnO films.Zinc oxide (ZnO) films have the potential in the emerging thin-film technologies which can be employed in thin-film solar cells, transistors, sensors and other optoelectronic devices. In this work, low cost sol–gel spin-coating technique was used to synthesize the ZnO films. The influences of annealing temperature on the structural and optical properties of ZnO and aluminum doped ZnO (AZO) films were investigated. The structural properties of the ZnO films such as surface morphology and crystallinity were determined using atomic force microscopy (AFM) and X-ray diffractometry (XRD), respectively. The optical properties of the ZnO films were characterized by the ultraviolet–visible (UV–vis) spectroscopy and Tauc method was adopted to estimate the optical gap. The experimental results reveal that the thermal annealing treatment affects the properties of the ZnO films. The effects of the low range annealing temperature on the sol–gel ZnO films addressed in this investigation will be discussed in this paper.
Keywords: ZnO films; AZO; Sol–gel spin coating; Thermal annealing;
Low temperature deposition of silver sulfide thin films by AACVD for gas sensor application by Syed Tajammul Hussain; Shahzad Abu Bakar; BiBi Saima; Bakhtiar Muhammad (9610-9616).
Display Omitted► Silver sulfide thin films were deposited by aerosol assisted chemical vapor deposition from a single source precursor [Ag(S2CN (C2H5)2)3]2 (1). ► The precursor (1), prepared in high yield by simple reported chemical procedure, was characterized and undergoes facile decomposition at 400 °C. ► The deposited thin films were characterized by SEM, EDX and XRD which suggests the formation of impurity-free mesoporous Ag2S, with well defined particles evenly distributed in the range of 0.3–0.5 μm. ► The optical bandgap energy of the thin film was estimated, and it is about 1.33 eV. ► The thin films were investigated for the gas sensor applications.Crack free Ag2S thin films were deposited on glass substrates by aerosol assisted chemical vapor deposition (AACVD) using [Ag(S2CN (C2H5)2)3]2 (1) as a precursor. Thin films were deposited from solution of methanol at 400 °C and characterized by X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. SEM image of thin film showed well-defined and porous surface morphology with an average particle size of 0.3–0.5 μm. Optical band gaps energy of 1.33 eV was estimated for Ag2S thin film, by extrapolating the linear part of the Tauc plot recorded at room temperature. The gas sensing characteristics of the novel gas sensors based on Ag2S were investigated for the detection carbon monoxide. The effect of operating temperature and change in gas concentration on the performance of carbon monoxide were investigated. The sensing mechanism of sensor was discussed.
Keywords: AACVD; Ag2S; Thin film; CO sensor; Band gap;
Ion beam sputter deposition of epitaxial Ag films on native oxide covered Si(1 0 0) substrates by C. Khare; J.W. Gerlach; C. Patzig; B. Rauschenbach (9617-9622).
► Ag(2 0 0) epitaxial films were grown on native oxide covered Si(1 0 0) substrates. ► With increased temperature the fraction of (2 0 0) oriented Ag crystallites increased. ► The lowest epitaxial growth temperature observed was 100 °C. ► For epitaxial films: a non-negligible oxygen content was noticed at the Ag/Si interface. ► SIMS measurement suggested local-desorption of native oxide layer during growth.Epitaxial Ag films were grown on native oxide covered Si(1 0 0) substrates by an ion beam sputter deposition process at elevated deposition temperatures. At RT, films were observed to be non-epitaxial but with preferred (1 1 1) orientation. However, elevated substrate temperatures and under highly energetic sputter deposition process assist the growth of Ag films, that exhibit an epitaxial relationship with the underlying Si(1 0 0) substrates. With increasing deposition temperature an increase in the crystalline quality was observed with a narrowing mosaic distribution of crystallites and a decrease in the fraction of 1st order twins. The lowest epitaxial growth temperature was observed to be as low as 100 °C.
Keywords: Ag thin film; Epitaxy; Sputter deposition; Native oxide;
Ultrathin films of Cu on Ru ( 1 0 1 ¯ 0 ) : Flat bilayers and mesa islands by J. Brona; R. Wasielewski; A. Ciszewski (9623-9628).
► The pseudomorphic Cu films grow in the bilayer-by-bilayer mode. ► For coverage higher than 2 BL, Cu forms 3D islands in mesa shape. ► The mesas have Cu(1 1 1) facets on their tops. ► The facets and the substrate are oriented with Cu ( 1 1 1 ) | | Ru ( 1 0 1 ¯ 0 ) and Cu [ 0 1 1 ¯ ] | | Ru [ 1 2 ¯ 1 0 ] .The Cu/Ru ( 1 0 1 ¯ 0 ) adsorption system was investigated by STM, LEED and AES. Cu was deposited at room temperature (RT) and 800 K, with the coverage ranging from a fraction up to 4 bilayers (BL). The first two Cu BL grow in the bilayer-by-bilayer mode. Their structure is pseudomorphic and does not depend on the temperature. For coverage higher than 2 BL, Cu deposited at elevated temperature forms three-dimensional islands in mesa shape with Cu(1 1 1) facets on their tops. The facets and the substrate are epitaxially oriented with Cu ( 1 1 1 ) | | Ru ( 1 0 1 ¯ 0 ) and Cu [ 0 1 1 ¯ ] | | Ru [ 1 2 ¯ 1 0 ] . Obtained results can be helpful in search for an optimal method of Cu deposition onto Ru in the damascene process in microelectronics, and could be also of interest to catalysis.
Keywords: Metallic surfaces; Ruthenium; Copper; Scanning tunneling microscopy (STM); Low-energy electron diffraction (LEED); Auger electron spectroscopy (AES);
Adsorption of carbon monoxide on Ag(I)-ZSM-5 zeolite: An ab initio density functional theory study by Zhen-Zhen Qiu; Yang-Xin Yu; Jian-Guo Mi (9629-9635).
Display Omitted► Significant difference in adsorption energy is found for CO adsorbed on different Ag+-exchange sites. ► Energetically stable sites in Ag–ZSM-5 are found. ► Introduction of the two Al atoms to the site of Ag–ZSM-5 results in a reduction of CO adsorption energy. ► Comparison of CO adsorption energy on the corresponding charge-exchange sites of Ag–ZSM-5 and Cu–ZSM-5 is made.Adsorption of carbon monoxide on different Ag+-exchange sites of Ag–ZSM-5 zeolite has been investigated using density functional theory. The coordination and local geometry of the Ag+ ion in Ag–ZSM-5 as well as adsorption structures and energies of CO adsorbed on these sites are explored extensively. The structure of Ag+-exchange sites, location of the Al atom on the T site, and number of the Al atoms contained in the sites are considered in the theoretical calculations. The calculated results show that the Ag―O coordination number of two is strongly preferred before and after CO adsorption. The Ag―O bond lengths are in a broad range of 2.2–2.9 Å, and the Ag―C bond lengths for CO adsorbed on Ag–ZSM-5 zeolite are calculated to be 2.0–2.2 Å. Both Ag―O and Ag―C bond lengths for CO–Ag–ZSM-5 complex are longer than those for CO–Cu–ZSM-5 complex. The calculated adsorption energy of CO adsorbed on the I2 sites is between 28.5 and 29.6 kcal/mol, and that on the Z5, Z6, M5 and M6 sites containing one Al atom on the T position is between 11.3 and 18.9 kcal/mol whereas the calculated adsorption energy of CO adsorbed on the M7 site containing one Al atom is 19.9 kcal/mol. The introduction of the two Al atoms to the Ag+-exchange site results in a reduction of CO adsorption energy. In general, the adsorption energy of CO on Ag–ZSM-5 is lower than that on Cu–ZSM-5. The predicted coordination of the Ag+ ion, bond lengths of Ag―O and Ag―C as well as adsorption energy are in accord with available experimental results.
Keywords: Density functional theory; Ag–ZSM-5; CO adsorption energy; Coordination number;
Surface conduction at phase transitions in (Au,Ag)/Si(1 1 1) submonolayer films by D.A. Tsukanov; M.V. Ryzhkova; E.A. Borisenko; L.V. Bondarenko; A.V. Matetskiy; D.V. Gruznev; A.V. Zotov; A.A. Saranin (9636-9641).
► Structural reordering occurs upon Ag adsorption onto Si(1 1 1)α-√3 × √3-Au surface phase at 350 °C. ► The new surface structure identified as Si(1 1 1)√93 × √93-(Au,Ag) has been found by LEED and STM. ► Electrical conductivity of various (Au,Ag)/Si(1 1 1) nanostructures has been characterized.Surface structure and electrical conductance of the (Au,Ag)/Si(1 1 1) two-dimensional system have been studied in situ with low-energy electron diffraction, scanning tunneling microscopy and four-point probe technique. The new surface structure identified as Si(1 1 1)√93 × √93-(Au,Ag) has been found to form upon deposition of ∼0.1 ML of Ag onto Si(1 1 1)α-√3 × √3-Au surface held at 350 °C. With further Ag deposition at this growth temperature, the surface structure evolves to Si(1 1 1)2√3 × 2√3 and eventually to Si(1 1 1)√21 × √21. Structural transformations have been found to be accompanied by non-monotonous changeover of the surface conductance. Possible factors affecting the surface conductivity are discussed.
Keywords: Surface electrical conductance; Scanning tunneling microscopy; LEED; Silicon; Gold; Silver; Compound;
Study on nanocomposite Ti–Al–Si–Cu–N films with various Si contents deposited by cathodic vacuum arc ion plating by J. Shi; C.M. Muders; A. Kumar; X. Jiang; Z.L. Pei; J. Gong; C. Sun (9642-9649).
► XRD peaks show a tendency of decreasing intensity with increasing Si content. ► Ti–Al–Si–Cu–N films present different microstructure with increasing Si content. ► Films with 6 at.% Si content obtain the highest hardness, elastic modulus and H 3/E 2. ► The wear rate decreases with an increase in hardness.In this study, nanocomposite Ti–Al–Si–Cu–N films were deposited on high speed steel substrates by the vacuum cathode arc ion plating (AIP) technique. By virtue of X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM), the influence of silicon content on the film microstructure and characteristics was investigated systematically, including the chemical composition, crystalline structure as well as cross-section morphologies. With increasing the silicon content, a deterioration of the preferred orientation and a dense globular structure were detected. In the meanwhile, atomic force microscopy (AFM), nano-indentation, Rockwell indenter and reciprocating test were also utilized to analyze the hardness, elastic modulus, H 3/E 2, friction coefficient, adhesive strength and wear rate of the Ti–Al–Si–Cu–N films. The results showed that an optimal silicon content correlated with the best mechanical and tribological properties of the presented Ti–Al–Si–Cu–N films existed. With increasing the silicon content, the hardness, elastic modulus and the ratio H 3/E 2 first were improved gradually, and then were impaired sharply again. When the silicon content reached to 6 at.%, the film possessed the highest hardness, elastic modulus and ratio H 3/E 2 of approximately 24 GPa, 218 GPa and 0.31, respectively. Besides, films containing both 6 at.% and 10 at.% Si contents obtained a relatively low friction coefficient and a good adhesive strength. The wear rate decreased with an increase in hardness, with the highest hardness corresponding to a wear rate around 1.3 × 10−5 mm3/(N m) of the film with 6 at.% Si content. The correlations between hardness and tribological properties for the films were also examined. The essence of above phenomena was attributed to the variations of microstructure and morphologies in the films induced by the increasing silicon content.
Keywords: Ti–Al–Si–Cu–N films; Cathode arc ion plating; Nanocomposite;
Fabrication of V2O3/C core–shell structured composite and VC nanobelts by the thermal treatment of VO2/C composite by Yifu Zhang; Meijuan Fan; Ling Hu; Weibing Wu; Juecheng Zhang; Xinghai Liu; Yalan Zhong; Chi Huang (9650-9655).
► Belt-like V2O3/C core–shell structured composite has been successfully synthesized. ► Vanadium carbide (VC) has been successfully synthesized. ► The carbon coated on the surface of V2O3 and VC is amorphous. ► Some C–H groups remain in the as-obtained V2O3/C and VC. ► VC has good thermal stability and oxidation resistance below 335 °C in air.Belt-like V2O3 encapsulated into carbon tubes (V2O3/C) core–shell structured composite and vanadium carbide (VC) nanobelts have been successfully synthesized by the thermal treatment with VO2/C core–shell structured composite through adjusting the heating temperature for the first time. The amorphous carbon on the surface of VO2 plays a dual role in this thermal process, namely as the reductant to reduce VO2 to V2O3 or VC, and as the carbon precursor for the V2O3/C carbon shell and VC. The as-obtained samples were respectively characterized by X-ray powder diffraction, energy-dispersive X-ray spectrometer, Raman spectrum, elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller. V2O3/C was successfully synthesized at 700–900 °C for 2 h, and VC nanobelts were successfully prepared at 1000 °C for 2 h. The as-obtained V2O3/C composite and VC nanobelts contain C–H groups, which will facilitate the linkage of catalytic species or polymers to the surface in their potential applications. V2O3/C composite has higher specific surface area than that of VC due to the amorphous carbon coated on the surface of V2O3. Furthermore, the thermal stability of VC in air was investigated by Thermo-Gravimetric/Differential Thermal Analyzer, revealing that it had good thermal stability and oxidation resistance below 335 °C in air.
Keywords: Nanocomposite; Core–shell structure; V2O3/C; VC; Interface reaction;
Effects of the AFM tip trace on nanobundles formation on the polymer surface by Yongda Yan; Yang Sun; Yanting Yang; Zhenjiang Hu; Xuesen Zhao (9656-9663).
► The AFM tip is used to scratch the PC surface once to form nanobundle structures. ► Effects of the tip trace on bundles formation are studied based on a modified AFM. ► The sample scanning mode is feasible for perfect nanobundle structures formation.Atomic Force Microscope (AFM) has become a popular experimental tool for the nanotribological studies. Nanobundles formation perpendicular to the scanning direction has been reported as a typical wear mode for the thermoplastics, and such bundle structures are also considered as sinusoidal wave micro-/nanostructures now. In the present study, the AFM tip based nanomechanical machining method is employed to scratch a polymer Polycarbonate (PC) surface for only once with the normal load of several micro-Newtons in order to achieve the perfect regular nanobundle structures. Based on a modified AFM system, effects of different tip traces in the tip scanning mode and in the sample scanning mode on nanobundles formation on the PC surface are studied. The experimental results show that the controlled reciprocal movement of the stage in the sample scanning mode is feasible for perfect nanobundle structures formation. Moreover, effects of the normal load and the feed on bundles formation in the sample scanning mode are analyzed. Experimental results reveal that the feed value directly affects the formed patterns including the bundles and grooves structures. The reciprocal effect of the tip trace is the decisive factor of forming ideal nanobundles. The repeating times on the same area acted by the tip which are larger than twice are necessary to form a perfect nanobundle structure.
Keywords: AFM; Scratch; Bundles; Polycarbonate (PC);
Low-temperature synthesis of mesoporous TiO2 photocatalyst with self-cleaning strategy to remove organic templates by Sheng Chu; Leilei Luo; Juncheng Yang; Fei Kong; Si Luo; Ying Wang; Zhigang Zou (9664-9667).
A low-temperature route combined solvothermal and self-cleaning strategy was developed to prepare crystalline mesoporous TiO2 with high photocatalytic activity.Display Omitted► A low-temperature method is developed to prepare mesoporous TiO2 photocatalyst. ► A self-cleaning strategy is used to completely remove organic templates. ► The mild method favors to retain the original mesostructure. ► The prepared sample exhibits excellent photocatalytic property. ► The method is expected to prepare other mesoporous photocatalysts.A novel low-temperature method integrated solvothermal and self-cleaning technique has been developed to prepare mesoporous TiO2 photocatalyst using triblock copolymers P123 as templates. The organic templates could be removed completely by the self-cleaning strategy under simulated sunlight irradiation. The product is characterized by FTIR, TG, XRD, N2 adsorption–desorption isotherms and TEM. The mild condition of the method is advantageous to retain the mesostructure compared with the calcination procedure. Further study indicates that the sample displays a higher photocatalytic activity for MO degradation than that of calcined sample, which could be attributed to its higher surface area, smaller crystal size and larger surface hydroxyl content.
Keywords: Titania; Template; Porous materials; Solar energy materials; Photocatalysis;
Experimental and theoretical studies on electrochemical synthesis of poly(3-amino-1,2,4-triazole) by Başak Doğru Mert; M. Erman Mert; Gülfeza Kardaş; Birgül Yazıcı (9668-9674).
Display Omitted► The poly(3-amino-1,2,4-triazole) was electrochemically synthesized. ► The homogeneous, colorful polymer has higher thermal and electrochemical stability. ► The correlation was observed between experimental and theoretical data.The electrochemical synthesis of poly(3-amino-1,2,4-triazole) (PATA) on the platinum (Pt) electrode was achieved in ammonium oxalate solution by cyclic voltammetry technique. The conductivity of film was measured with four probe technique, the surface morphology was monitored with atomic force microscopy (AFM) and characterization was achieved by Fourier transform infrared spectroscopy (FT-IR) and UV–vis spectroscopy techniques. The thermal stability of polymer has also been investigated by the means of thermogravimetric analysis (TGA). The electrochemical stability of Pt/PATA was investigated in different buffer solutions. The quantum theoretical calculations employed and some parameters (dipole moment, E HOMO, E LUMO) were determined.
Keywords: Electropolymerization; Poly(3-amino-1,2,4-triazole); Atomic force microscopy; Thermogravimetric analysis; Quantum theoretical calculation;
Au-assisted Co silicide island growth on Si(1 1 1) by A. Fleurence; G. Agnus; T. Maroutian; B. Bartenlian; P. Beauvillain (9675-9679).
► Au is known to favor the formation of CoSi2 by solid phase reaction of Co with Si. ► We investigated the formation of Co silicide islands in presence of Au-rich islands. ► Au-rich islands induce locally an extraction of Si atoms out of the substrate. ► Si atoms outdiffusion decreases the formation temperature of Co silicide islands.Based on a local study by means of scanning tunneling microscopy, we demonstrate that a small amount of Au grown on Si(1 1 1) either as Au-induced surface reconstruction or Au-rich islands, promotes dramatically the growth of Co silicide islands by solid phase reaction. We identified an outdiffusion of Si atoms from the substrate, induced by the Au-rich islands and limited to their vicinity, which results in a strong decrease of the formation temperature of the silicide islands.
Keywords: Co silicide nanostructures; Solid phase reaction; Au–Si islands; Self-organization;
Fabrication of porous flaky electromagnetic particles by electroless plating of CoNiP on diatomite by Liming Yuan; Jun Cai; Wenqiang Zhang; Zhiyang Lian; Deyuan Zhang (9680-9684).
► The lightweight porous flaky electromagnetic particles were fabricated with deposition of CoNiP coating onto the diatomite templates. ► A coupling processing was applied to improve the effect of activation and electroless plating of diatomite. ► The CoNiP coating on the diatomite was a transitional structure between crystal and amorphousness. ► The fabricated micro flaky electromagnetic particles had promising electromagnetic properties.In order to fabricate lightweight flaky electromagnetic particles efficiently, the diatomite was used as the forming template to which the CoNiP coating was deposited by an electroless plating technique. The electroless plating of CoNiP on diatomite was accomplished with the coupling processing before the activation, in which 3-aminopropyltriethoxysilane (APTES) was used as the coupling agent. The effect of coupling processing on the activation and electroless plating of diatomite was characterized by SEM, FT-IR and EDS analysis. The results indicated that with coupling processing before activation, the catalytic effect was improved remarkably than that of direct colloidal palladium activation, which resulted in superior electroless plating on diatomite, even on the surface of submicron holes. The XRD analysis showed that the CoNiP coating was a transitional structure between crystal and amorphousness. The measurement of complex permeability and permittivity in the range of 2–18 GHz suggested that the micro flaky electromagnetic particles had promising electromagnetic properties.
Keywords: Diatomite; Coupling processing; Electroless plating; Porous flaky particle; Electromagnetic property;
Direct monophasic replacement of fatty acid by DMSA on SPION surface by M. Gogoi; P. Deb; G. Vasan; P. Keil; A. Kostka; A. Erbe (9685-9691).
Display Omitted► Monophasic replacement of fatty acid coating. ► Ultrastable dispersion of hydrophilic SPION in a wide pH range. ► Unaltered microstructure and property on surface modification.Tailoring the surface and understanding the surface characteristics is necessary for biomedical applications of superparamagnetic nanoparticles. In this paper, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared by thermal decomposition of iron nitrate in presence of stearic acid as surfactant. Due to the multilayer organization of surfactant molecules over the nanoparticle surface, the surface potential can be tuned by pH changes and hence the nanoparticles can be made dispersible in nonpolar as well as in polar solvents. We have presented a simple, facile procedure for controlled replacement of stearic acid from maghemite surface and subsequent derivatization by biocompatible dimercaptosuccinic acid (DMSA) to obtain ultrastable hydrophilic nanoparticles with unaltered morphology, phase and properties. The surface chemistry of the functionalized SPIONs was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) revealing the presence of bound and unbound thiol groups and disulfides, leading to its prolonged stability in aqueous medium. The consequence of spatially selective functionalization on the stability and solubility of surface hydrophilic SPION has also been realized.
Keywords: Controlled replacement; Surface characteristics; Hydrophilic; SPION;
Electroless ternary NiCeP coatings: Preparation and characterisation by J.N. Balaraju; Manju Chembath (9692-9700).
► Rare earth element (Ce) has been successfully codeposited in NiP matrix. ► Surface analysis carried out by XPS showed that the Ce is present in +3 and +4 oxidation state. ► Palladium stability test indicated that the Ce salts in electroless nickel bath has reduced the stability. ► Cerium codeposition in NiP matrix has increased the microhardness both in as-plated and annealed conditions. ► Higher thermal stability has been obtained by Ce incorporation.Electroless ternary NiCeP deposits were prepared from alkaline citrate bath containing nickel sulphate, cerium chloride and sodium hypophosphite. Concentration of rare earth cerium was varied from 1 to 2 g/L to obtain ternary deposits containing variable Ce and P contents. The influence of cerium on the deposit properties was analysed. The deposit exhibited a maximum cerium content of 6.2 ± 0.1 wt.% when the cerium chloride concentration was 2 g/L. The result of the Pd stability test showed that the stability of the bath was reduced due to Ce salt addition. The microhardness measurements made on both as-plated and heat treated samples exhibited a peak hardness of 1006 ± 11 VHN for cerium concentration of 1.5 g/L. The concept of kinetic strength analysis was proved to be applicable only for binary and not for ternary alloys due to multistep deposition mechanism with different kinetic energies. X-ray diffraction (XRD) patterns of as-plated and heat treated samples revealed peaks corresponding to Ni (1 1 1) and nickel phosphide (Ni3P). Higher amount of Ce incorporation in NiP matrix increased the crystallisation temperature of the deposit which could be due to the suppression of nickel crystallisation prior to Ni3P compound formation and thus increasing the activation energy for the formation of stable phases. Surface compositional analysis using X-ray photoelectron spectroscopy (XPS) carried out on as-plated NiCeP-2 deposit showed a prominent peak of P existing in +1 oxidation state as higher alkalinity favoured hypophosphite deposition in the ternary alloy coating. It was observed that the co-deposition of Ce in NiP matrix improved the continuous salt spray exposure for 168 h.
Keywords: Electroless NiCeP; Morphology; Microhardness; Thermal stability; XRD; XPS;
Chemical vapor deposition growth of InN nanostructures: Morphology regulation and field emission properties by Fan Zhang; Qiang Wu; Yongliang Zhang; Jianmin Zhu; Ning Liu; Jing Yang; Xizhang Wang; Zheng Hu (9701-9705).
► A series of InN nanostructures have been synthesized. ► InN nanomaterials were prepared by a chloride-sourced chemical vapor deposition method. ► The morphologies of InN nanostructures were regulated by changing the growth conditions. ► InN nanocones showed potential applications in field emission devices.The facile synthesis of InN nanostructures is of great importance due to their wide potential applications in (opto)electronic devices. Herein we reported the synthesis of InN nanostructures through a convenient chloride-sourced chemical vapor deposition method with simple processing and free of catalyst. The morphologies of the InN products were regulated from one-dimensional nanocones and hexagonal nanoprisms to octahedrons and four-fold-symmetrical InN hierarchical nanostructures by varying the vaporization temperature of InCl3 and deposition temperature. The formation mechanism of the InN nanostructures has been discussed on the basis of the change in InCl3 vapor pressure and the morphological evolution under different temperature. The field emission properties of the InN nanocones were evaluated due to their unique sharp apex geometry, which showed a turn on field of ∼12 V/μm, suggesting their potential application in field emission devices.
Keywords: Indium nitride; Nanostructures; Chemical vapor deposition; Field emission; Morphology;
Effect of annealing on composition, structure and optical properties of SrHfON thin films by Li-ping Feng; Yin-quan Wang; Hao Tian; Zheng-tang Liu (9706-9710).
► Novel SrHfON thin films were prepared by RF magnetron reactive sputtering. ► SrHfON films remain amorphous after 900 °C annealing. ► Refractive index increases while extinction coefficient decreases after annealing. ► The annealed SrHfON films have higher ɛ 1 and lower ɛ 2 than as-deposited SrHfON film.SrHfON thin films were deposited on Si substrate by radio frequency (RF) magnetron reactive sputtering. Composition, structure and optical properties of the SrHfON films in relation to rapid thermal annealing (RTA) temperatures were analyzed by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and spectroscopic ellipsometry (SE). The XPS analysis indicates that the peaks of Sr 3d, Hf 4f, O 1s, and N 1s shift toward higher binding energy after the RTA treatment. The XRD results show that the SrHfON films remain amorphous after RTA treatment at 900 °C. Optical constants of the as-deposited and annealed SrHfON films are extracted based on a parameterized Tauc–Lorentz (TL) model. With the increase of annealing temperatures, the refractive index increases while the extinction coefficient decreases. The annealed SrHfON films have higher ɛ 1 and lower ɛ 2 than the as-deposited SrHfON films. Moreover, the extracted indirect bandgap values are 4.98, 5.06, and 5.18¦eV for the as-deposited and annealed SrHfON thin films at 600 and 900 °C, respectively.
Keywords: SrHfON film; RTA; Optical properties; Spectroscopic ellipsometry;
Fabrication of cell outer membrane mimetic polymer brush on polysulfone surface via RAFT technique by Qian Ma; Hui Zhang; Jiang Zhao; Yong-Kuan Gong (9711-9717).
Display Omitted► Cell membrane mimetic antifouling polymer brush was grown on polysulfone surface. ► Graft density and polymerization degree were calculated from XPS results. ► Water contact angle measurements showed an extremely hydrophilic surface. ► Platelet adhesion and protein adsorption results suggested excellent antifouling ability.Cell membrane mimetic antifouling polymer brush was grown on polysulfone (PSF) membrane by surface-induced reversible addition–fragmentation chain transfer (RAFT) polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC). The RAFT agent immobilized PSF substrate was prepared by successive chloromethylation, amination with ethylenediamine (EDA) and amidation of the amine group of grafted EDA with the carboxylic group of 4-cyanopentanoic acid dithiobenzoate (CPAD). The surface RAFT polymerization of MPC was initiated in aqueous solution by 4,4′-azobis-4-cyanopentanoic acid (ACPA). The formation of PMPC brush coating is evidenced by X-ray photoelectron spectroscopy and water contact angle measurements. The degree of polymerization of PMPC and the polymer grafting density were calculated from the high resolution XPS spectra. The platelet adhesion and protein adsorption results showed that the PMPC-grafted PSF surface has excellent antifouling ability to resist platelet adhesion completely and suppress protein adsorption significantly. This biomimetic and bio-friendly surface RAFT polymerization strategy could be promising for a variety of biomedical applications.
Keywords: Surface modification; Phosphorylcholine; RAFT polymerization; Antifouling surface; Polysulfone;
Template-assisted fabrication of tin and antimony based nanowire arrays by Leszek Zaraska; Elżbieta Kurowska; Grzegorz D. Sulka; Marian Jaskuła (9718-9722).
Display Omitted► The arrays of Sb/Sb2O3 and Sn–SnSb nanowires were synthesized by electrodeposition. ► The shape of nanowires depends on the structural features of the AAO template. ► The composition of the materials depends on the electrodeposition conditions.Antimony nanowires with diameters ranging from 35 nm to 320 nm were successfully prepared by simple, galvanostatic electrodeposition inside the pores of anodic alumina membranes from a citrate based electrolyte. The use of the potassium antimonyl tartrate electrolyte for electrodeposition results in the formation of Sb/Sb2O3 nanowires. The structural features of the nanowire arrays were investigated by FE-SEM, and the nanowire composition was confirmed by EDS and XRD measurements. A distinct peak at about 27.5° in the XRD pattern recorded for nanowires formed in the tartrate electrolyte was attributed to the presence of co-deposited Sb2O3. Three types of dense arrays of Sn–SnSb nanowires with diameters ranging from 82 nm to 325 nm were also synthesized by DC galvanostatic electrodeposition into the anodic aluminum oxide (AAO) membranes for the first time. Only Sn and SnSb peaks appeared in the XRD pattern and both phases seem to have a relatively high degree of crystallinity. The influence of current density applied during electrodeposition on the composition of nanowires was investigated. It was found that the Sb content in fabricated nanowires decreases with increasing current density. The diameters of all synthesized nanowires roughly correspond to the dimensions of the nanochannels of AAO templates used for electrodeposition.
Keywords: Tin; Antimony; Nanowires; Electrodeposition;
Dual-scale rough multifunctional superhydrophobic ITO coatings prepared by air annealing of sputtered indium–tin alloy thin films by Nitant Gupta; S. Sasikala; D.B. Mahadik; A.V. Rao; Harish C. Barshilia (9723-9731).
► Sputtered indium–tin coatings were annealed in air to generate superhydrophobic surfaces. ► The coatings also showed multifunctional properties, viz., semi-transparency, conductivity and photoluminescence. ► Dual scale roughness of the samples was detected using FESEM, rendering the drops to be in Cassie wetting state. ► Chemical nature and structure of the coatings was examined by XRD, XPS and micro-Raman analyses. ► The other properties were examined by absorption spectra, sheet resistance and PL spectra measurements.A novel method to fabricate multifunctional indium tin oxide (ITO) coatings is discussed. Superhydrophobic ITO coatings are fabricated by radio frequency balanced magnetron sputter deposition of indium–tin alloy on glass substrates followed by complete oxidation of the samples in air. The chemical nature and structure of the coatings are verified by X-ray diffraction, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. Field emission scanning electron microscopic studies of the coatings display rod-like and blob-like microstructures, together with fractal-like nanostructures infused on top. Microscale roughness of the ITO coatings is measured by three-dimensional profilometry and is found to be in the range of 0.1–3 μm. Thus the presence of micro- and nano- sized structures result in dual-scale roughness. The variation in the contact angle with the deposition time is studied using a contact angle goniometer. High water contact angles (>160°) and low contact angle hysteresis (5°) are obtained at an optimum microscale roughness. The ITO coatings also exhibit other functional properties, such as low sheet resistance and semi-transparent behaviour in the visible region. The loss in the transparency of the ITO coatings is attributed to the presence of higher scale of roughness. The photoluminescence measurements show large photoemission in the visible region. It is expected that further improvements in the multifunctional properties of transparent conducting oxides will open new frontiers in designing novel materials with exotic properties.
Keywords: Indium tin oxide; Superhydrophobic surface; Dual-scale roughness; Multifunctional;
Local absorptivity modulation of a 1 μm-laser beam through surface waviness by Alexander F.H. Kaplan (9732-9736).
► Glancing absorptivity of 1 μm lasers across a wavy molten steel surface. ► Even low roughness causes strong, complex local absorptivity modulation. ► For moderate and high roughness shadow domains gradually lower absorptance. ► Important consequences for laser welding, cutting, drilling. ► Angle- and wavelength-dependent Fresnel-curves determine absorption at rough surfaces.In laser materials processing operations such as deep penetration laser welding, the laser beam often interacts with a wavy, molten surface. This wavy topology strongly modulates the local angle of incidence of the laser rays across the surface and in turn the local absorptivity, which is described by the Fresnel-equations. In this paper this modulation of the absorptivity is modelled over a two-dimensional steel surface for prescribed wavy topology for high power lasers with a wavelength of about 1 μm, like disc, fibre, Nd:YAG or diode lasers. It has become apparent that even a topology with regular peaks and valleys causes a complex absorptivity distribution at the surface, including significant shadowing domains due to the grazing angle of incidence during processes like laser welding, drilling or cutting. In contrast to a smooth melt, the waviness tends towards an angle-averaged absorptivity, of 33% for 1 μm-lasers and steel. The high sensitivity of the absorptivity and of shadowing on the surface topology significantly modulates the local absorptivity of the beam power density and in turn the local process mechanisms, such as boiling accompanied by recoil pressure.
Keywords: Laser; Wavy surface; Roughness; Absorptivity; Absorption; Welding;
Sulfonation of polyester fabrics by gaseous sulfur oxide activated by UV irradiation by Bessem Kordoghli; Ramzi Khiari; Mohamed Farouk Mhenni; Faouzi Sakli; Mohamed Naceur Belgacem (9737-9741).
► In this paper, an original technique was present to improve the hydrophilic properties of polyester fibres. ► The modification of PET fabric was carried out using gaseous sulfur trioxide activated by UV irradiations. ► We fully characterized the modified and untreated fabrics.This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of ―SO3H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.
Keywords: Sulfonation; UV irradiation; PET fabric; Hydrophilic properties;
Laser-induced front side and back side etching of fused silica with KrF and XeF excimer lasers using metallic absorber layers: A comparison by Pierre Lorenz; Martin Ehrhardt; Klaus Zimmer (9742-9746).
► We study laser-induced front and back side etching of fused silica with a KrF and a XeF excimer laser. ► Chromium layers as absorber are used. ► The LIFE method allows nm-precision etching with etching depths up to 300 nm. ► The measurement results are compared to the results calculated by a thermal model.Laser-induced front side (LIFE) and back side etching (LIBDE) are methods for nanometer-precision laser etching of transparent materials using thin absorber layers. The etching behaviour of fused silica at a laser wavelength of 248 nm (KrF) and 351 nm (XeF excimer laser) with a pulse duration of 25 ns using a chromium absorber layer was analysed and compared for front and back side etching geometry. For both wavelengths as well as for both processes the etching depth d increases almost linearly in dependence on the laser fluence (it is: d ≈ δ*(Φ − Φ th)). The etching depth at the same laser fluence is higher for 248 nm compared to 351 nm as well as for back side etching compared to the front side etching process (LIFE: δ(248 nm) = 20 nm/(J/cm2), δ(351 nm) = 15 nm/(J/cm2), LIBDE: δ(248 nm) = 38 nm/(J/cm2), δ(351 nm) = 8 nm/(J/cm2) with Φ th,m from 0.3 to 2.65 J/cm2). Furthermore, the measured depths were evaluated with the estimated etching depth calculated by a thermal model. The simple thermodynamic model allows a good qualitative description of the etching depth behaviour; however, the model does not allow the quantitative calculation of the etching depth.
Keywords: LIFE; LIBDE; Laser etching; Metallic adsober; Fused silica;
Triangle islands and cavities on the surface of evaporated Cu(In, Ga)Se2 absorber layer by Anjun Han; Yi Zhang; Wei Liu; Boyan Li; Yun Sun (9747-9750).
Display Omitted► Lots of uncommon triangle islands and cavities are found on (1 1 2) planes terminated by Se atoms of evaporated Cu(In, Ga)Se2 thin films. ► Se ad-dimer as a nucleus, Cu atom diffusion from Cu(In, Ga)Se2 grains brings the epitaxial triangle island. ► The triangle islands grow with a two-dimensional layered mode. ► The triangle cavities are formed due to the insufficient coalescence of triangle islands. ► The performance of solar cell without triangle islands is improved.Cu(In, Ga)Se2 (CIGS) thin films are co-evaporated at a constant substrate temperature of 500 °C on the Mo/soda lime glass substrates. The structural properties and chemical composition of the CIGS films are studied by an X-ray diffractometer (XRD) and an X-ray fluorescent spectrometer (XRF), respectively. A scanning electron microscope (SEM) is used to study the surface morphology. Lots of uncommon triangle islands and cavities are found on some planes of the CIGS thin films. We investigate the formation mechanism of these triangle islands. It is found that the planes with the triangle islands are (1 1 2) planes terminated by Se atoms. Se ad-dimer as a nucleus, Cu diffusion from CIGS grains brings the epitaxial triangle islands which grow with a two-dimensional layered mode. The film with Cu/(Ga + In) = 0.94–0.98 is one key of the formation of these islands. The triangle cavities are formed due to the insufficient coalescence of triangle islands. The growth of triangle islands brings a compact surface with large layered grains and many jagged edges, but no triangle cavity. Finally, we compare the performance of solar cell with triangle islands and layered gains. It is found that the performance of solar cell with large layered gains is improved.
Keywords: Cu(In, Ga)Se2 thin film; Triangle islands; Cavities; Growth; Solar cell;
Direct observation of phase transition of GeSbTe thin films by Atomic Force Microscope by Fei Yang; Ling Xu; Rui Zhang; Lei Geng; Liang Tong; Jun Xu; Weining Su; Yao Yu; Zhongyuan Ma; Kunji Chen (9751-9755).
Nano-sized marks on GST thin film were fabricated using Conductive-AFM (Atomic Force Microscope). The AFM morphology images show that the marks are ablated at the center and a raised ring surrounding it.Display Omitted► Microstructure of GeSbTe thin films was characterized by XRD and AFM. ► Annealing and applying electrical field can induce crystallization on thin film. ► Conductive-AFM was used to modify the surface of GeSbTe thin film.GeSbTe (GST) thin films were deposited on quartz substrates using electron beam evaporation system and then annealed in nitrogen atmosphere at different temperatures, ranging from 20 °C to 300 °C. X-ray diffraction (XRD) and Atomic Force microscope (AFM) measurements were used to characterize the as-deposited and post-annealed thin films. Annealing treatment was found to induce changes on microstructure, surface roughness and grain size, indicating that with the increase of annealing temperature, the amorphous GST films first changed to face-centered-cubic (fcc) phase and then the stable hexagonal (hex) phase.Meanwhile, conductive-AFM (C-AFM) was used to produce crystallized GST dots on thin films. I–V spectroscopy results show that GST films can switch from amorphous state to crystalline state at threshold voltage. After switching, I–V curve exhibits ohmic characteristic, which is usually observed in crystallized GST films. By applying repeated I–V spectroscopies on the thin films, crystallized nuclei were observed. As the times of I–V spectroscopies increases, the area of written dots increases, and the center of the mark begin to ablate. The AFM images show that the shape of marks is an ablated center with a raised ring surrounding it.
Keywords: GeSbTe; Annealing; Phase change; XRD; AFM; C-AFM;
Mechanical characteristics of soft-brittle HgCdTe single crystals investigated using nanoindentation and nanoscratching by Hongxiu Zhou; Shuo Qiu; Xianzhong Zhang; Chaoge Xu (9756-9761).
► Both the shape and half included angle of the indenter tip affect the friction coefficient, as well as normally scratched depth. ► The hardness has an influence on the creeping event of MCT wafers. ► Size effect is observed for the nanohardness during nanoindentation, which is presented using indentation curvature.Mechanical characteristics of mercury cadmium telluride (HgCdTe or MCT) single crystals were investigated using microindentation, nanoindentation, nanoscratching, and in situ atomic force microscopy. All the scratched surfaces of polished MCT wafers at nano-scale exhibit plastic deformation, which is different from brittle nature at macro-scale. All the loading curves of nanoindentation agree well, when the normal loads varies from 1 to 8 mN. The elastic modulus is kept constant approximately at 50 GPa with the indentation depth varying from 200 to 800 nm. The hardness is remained constant basically at 0.35 GPa, as the indentation depth ranges from 2 to 15 μm. Friction coefficient is retained basically constant, despite of the increasing of applied normal load varying from 1000 to 5000 μN for nanoscratching. Size effect is observed for the nanohardness during nanoindentation, which is addressed using indentation curvature. The simulated results of size effect are consistent with those found experimentally.
Keywords: Nanoindentation; Nanoscratch; Hardness; Size effect; HgCdTe;
Effects of annealing on arrays of Ge nanocolumns formed by glancing angle deposition by C. Khare; J.W. Gerlach; T. Höche; B. Fuhrmann; H.S. Leipner; B. Rauschenbach (9762-9769).
► Free-standing, polycrystalline Ge nanocolumn arrays are obtained by controlled thermal annealing. ► Annealing induces considerable morphology coarsening and re-crystallization at ∼500 °C. ► Nanostructures deposited on pre-patterned substrates retained their shape even at ∼700 °C. ► TEM investigation revealed nano-crystalline domains of the order of 5-30 nm within annealed nanostructures.Post-deposition thermal annealing of glancing angle deposited Ge nanocolumn arrays was carried out in a continuous Ar-flow at temperatures ranging from T A = 300 to 800 °C for different annealing durations. Morphological alterations and the recrystallization process induced by the thermal annealing treatment were investigated for the Ge nanocolumns deposited on planar and pre-patterned Si substrates. From X-ray diffraction (XRD) measurements, the films annealed at T A ≥ 500 °C were found to be polycrystalline. On planar Si substrates, at T A = 600 °C nanocolumns exhibited strong coarsening and merging, while a complete disintegration of the nanocolumns was detected at T A = 700 °C. The morphology of nanostructures deposited on pre-patterned substrates differs substantially, where the merging or column-disintegration effect was absent at elevated annealing temperatures. The two-arm-chevron nanostructures grown on pre-patterned substrates retained their complex shape and morphology, after extended annealing intervals. Investigations by transmission electron microscopy revealed nanocrystalline domains of the order of 5–30 nm (in diameter) present within the chevron structures after the annealing treatment.
Keywords: Glancing angle deposition; Ge nanocolumns; Thermal annealing; Re-crystallization;
Fouling propensity and separation efficiency of epoxidated polyethersulfone incorporated cellulose acetate ultrafiltration membrane in the retention of proteins by A. Jayalakshmi; S. Rajesh; D. Mohan (9770-9781).
Display Omitted► Epoxy functionalized polyethersulfone was prepared. ► CA/EPES ultrafiltration membranes were developed by phase inversion technique. ► Compatibility, morphology and separation efficiency of the membranes were studied. ► Fouling propensity of the membranes was studied by BSA as the model foulant. ► Degree reversible and irreversible fouling and flux recovery ratio were calculated.Epoxidated polyethersulfone (EPES) incorporated cellulose acetate (CA) ultrafiltration membranes were prepared by diffusion induced precipitation technique in the absence and presence of pore former polyethyleneglycol-600. Effect of blend ratio on the compatibility, thermal stability, mechanical strength, hydrophilicity, morphology, pure water flux, protein adsorption resistance, protein separation efficiency and fouling propensity of the CA/EPES blend membranes was evaluated. Addition of EPES results in the formation of thin separating layer and spongy sub layer in CA/EPES blend membranes. The efficiency of these membranes in the separation of commercially important proteins such as bovine serum albumin, egg albumin, pepsin and trypsin was studied and found to be enhanced as compared to CA membranes. The fouling-resistant capability of the membranes was studied by bovine serum albumin as the model foulant and flux recovery ratio of the membranes were calculated. Attempts have been made to correlate the changes in membrane morphology with pure water flux, hydraulic resistance, thermal and mechanical stability, separation efficiency and antifouling property of the CA/EPES membranes. The optimal combination of CA and EPES, thus allows the preparation of high performance UF membranes which are sufficiently dense to retain proteins and at the same time give economically viable fluxes.
Keywords: Ultrafiltration; EPES; SEM; AFM; Antifouling;
Fluorocarbon thin film with superhydrophobic property prepared by pyrolysis of hexafluoropropylene oxide by Jun Wang; Xue Song; Rui li; Jinpeng Shen; Guangcheng Yang; Hui Huang (9782-9785).
► We successfully prepared nanostructured fluorocarbon thin films using CVD method without any catalysts at low pyrolysis temperature (200–300 °C) of HFPO. ► The films show disparate morphology, high content of CF2 (>90%), which are also characteristic of bulk PTFE. ► The film deposited at 300 °C shows superhydrophobic property (water contact angle of 172.7°).A fluorocarbon thin film with superhydrophobic property was prepared by chemical vapor deposition (CVD) method at low temperature (200–300 °C) via pyrolysis hexafluoropropylene oxide (HFPO). The experiment results indicated the morphology and structure of fluorocarbon films were strongly dependent on the pyrolysis temperature. As shown through atomic force microscope (AFM), the surface morphology of the films ranged from rodlike grains to sheets. Fourier transform infrared (FTIR) spectroscopy revealed that all the films contained the vibrational frequencies of linear CF2 chains, which were also characteristic of bulk poly tetrafluoroethylene (PTFE). X-ray photoelectron spectroscopy (XPS) analysis showed that CF2 structures were predominant in the films with high order. The film deposited at 300 °C exhibited a superhydrophobic surface with contact angle up to 172.7°.
Keywords: Low temperature pyrolysis; Thin film; Surface morphology; Superhydrophobic property;
Characteristics of phase transition and separation in a In–Ge–Sb–Te system by Sung Jin Park; Moon Hyung Jang; Seung-Jong Park; Mann-Ho Cho; Dae-Hong Ko (9786-9791).
► InGeSbTe films were fabricated via co-deposition stoichiometric GST and IST targets. ► As the amount of IST was increased in InGeSbTe, the value for V th and the phase transition temperature were increased. ► The phase separation in InGeSbTe is caused by differences in the enthalpy change for formation and different atomic concentrations.In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge2Sb2Te5 (GST) and In3Sb1Te2 (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point R s measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point R s data. In addition, in In28Ge12Sb26Te34, multiple V th values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In2Te3 occurred in all of the InGeSbTe samples after annealing at 350 °C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge–Te, In–Te, Sb–Te, In–Sb and In–In bond energies.
Keywords: PRAM; Chalcogenide; Phase change; Phase separation; InGeSbTe;
Facile morphological control of single-crystalline silicon nanowires by Shao-long Wu; Ting Zhang; Rui-ting Zheng; Guo-an Cheng (9792-9799).
.Display Omitted► The morphology of SiNWs is facilely controlled in a chemical etching method. ► The vertically-, slantingly-aligned and zigzag SiNW arrays are synthesized. ► Their surfaces can be controlled to be smooth and rough, with or without mesopores. ► The formation mechanisms of various morphologies of SiNWs are discussed.To realize wider potentials of silicon nanowires (SiNWs), the morphological controllability is desirable. In this paper, we synthesized well vertically- and slantingly-aligned SiNWs with ultra-high aspect ratio in metal-assisted chemical etching method, and wafer-scale zigzag SiNWs with three types of turning angle were also obtained. The formation of the curved SiNWs is a result of the alternation of moving direction of Ag nanoparticles between the preferred 〈1 0 0〉 and other directions in Si substrates. The as-prepared SiNWs are single-crystalline and their orientations are mostly along the 〈1 0 0〉 or 〈1 1 1〉 directions. The surface of the resulting SiNWs can be controlled to be smooth or rough, with or without mesopores, by adjusting the etching conditions and using various Si substrates with different crystal orientations and doping levels. Moreover, the effects of the etching conditions (etching time, oxidant concentration, deposition time of Ag nanoparticles and etching temperature) and substrate properties (crystal orientation and doping level) on the as-prepared SiNWs have been discussed.
Keywords: Morphological control; Vertically-aligned nanowires; Slanting-aligned nanowires; Zigzag silicon nanowires; Porosity; Rough surface;
Ruthenium Grubbs’ catalyst nanostructures grown by UV-excimer-laser ablation for self-healing applications by B. Aïssa; R. Nechache; E. Haddad; W. Jamroz; P.G. Merle; F. Rosei (9800-9804).
► Successful preparation of 5-Ethylidene-2-Norbornene (5E2N) monomer reacted with Ruthenium Grubbs’ Catalyst (RGC) composite. ► The kinetics of the 5E2N ring opening metathesis polymerization (ROMP) is effective in a large temperature range (−20 to 45 °C). ► The kinetics of the 5E2N ROMP is occurring at very short time scales (<1 min at 40 °C). ► Successful preparation of RGC nanoparticles (NPs) by UV-excimer laser ablation approach. ► The ROMP reaction associated to RGC-NPs was achieved at an unprecedented extreme low RGC, equivalent to 0.00117 Vol.%.A self healing composite material consisting of 5-Ethylidene-2-Norbornene (5E2N) monomer reacted with Ruthenium Grubbs’ Catalyst (RGC) was prepared. First, the kinetics of the 5E2N ring opening metathesis polymerization (ROMP) reaction RGC was studied as a function of temperature. We show that the polymerization reaction is still effective in a large temperature range (−15 to 45 °C), occurring at short time scales (less than 1 min at 40 °C). Second, the amount of RGC required for ROMP reaction significantly decreased through its nanostructuration by means of a UV-excimer laser ablation process. RGC nanostructures of few nanometers in size where successfully obtained directly on silicon substrates. The X-ray photoelectron spectroscopy data strongly suggest that the RGC still keep its original stoichiometry after nanostructuration. More importantly, the associated ROMP reaction was successfully achieved at an extreme low RGC concentration equivalent to (11.16 ± 1.28) × 10−4 Vol.%, occurring at very short time reaction. This approach opens new prospects for using healing agent nanocomposite materials for self-repair functionality, thereby obtaining a higher catalytic efficiency per unit mass.
Keywords: Grubbs’ catalyst; Laser ablation; Nanocomposite; Nanostructures; Self-healing materials;
Photocatalytic activity of Ag3PO4 nanoparticle/TiO2 nanobelt heterostructures by Ruoyu Liu; Peiguang Hu; Shaowei Chen (9805-9809).
► Ag3PO4-TiO2 heterostructures were prepared by a simple coprecipitation method. ► Photocatalytic activity of the heterostructures in the degradation of methyl orange. ► Efﬁcient separation of photogenerated electrons and holes in heterostructures. ► Marked improvement of the chemical stability and reusability of heterostructures.Heterostructures based on Ag3PO4 nanoparticles and TiO2 nanobelts were prepared by a coprecipitation method. The crystalline structures were characterized by X-ray diffraction measurements. Electron microscopic studies showed that the Ag3PO4 nanoparticles and TiO2 nanobelts were in intimate contact which might be exploited to facilitate charge transfer between the two semiconductor materials. In fact, the heterostructures exhibited markedly enhanced photocatalytic activity as compared with unmodified TiO2 nanobelts or commercial TiO2 colloids in the photodegradation of methyl orange under UV irradiation. This was accounted for by the improved efficiency of interfacial charge separation thanks to the unique alignments of their band structures. Remarkably, whereas the photocatalytic activity of the heterostructure was comparable to that of Ag3PO4 nanoparticles alone, the heterostructures exhibited significantly better stability and reusability in repeated tests than the Ag3PO4 nanoparticles.
Keywords: Ag3PO4 nanoparticle; TiO2 nanobelt; Photocatalysis; Methyl orange;
Photo-induced properties of non-annealed anatase TiO2 mesoporous film prepared by anodizing in the hot phosphate/glycerol electrolyte by Yoshiaki Taguchi; Etsushi Tsuji; Yoshitaka Aoki; Hiroki Habazaki (9810-9815).
► The TiO2 mesoporous film can be formed by anodizing of titanium specimens in the hot phosphate/glycerol electrolyte. ► The mesoporous film formed at 20 V without annealing was a mixture of amorphous phase and nanograined anatase, which clearly showed strong 〈0 0 1〉 preferred orientation. ► Even without annealing, the as-anodized anatase TiO2 mesoporous film showed high photocatalytic activities for decomposition of water and methylene blue. ► The as-anodized anatase TiO2 mesoporous film also showed superhydrophilicity with UV light irradiation.In this study, anatase crystalline TiO2 mesoporous film was formed by anodizing of titanium specimens without annealing procedures. The specimens were anodized at 3 and 20 V in 0.6 mol dm−3 K2HPO4 and 0.2 mol dm−3 K3PO4/glycerol electrolyte at 433 K. The obtained films had mesoporous structures with pore diameters as small as ∼10 nm. The mesoporous film formed at 20 V without annealing (MP-20V) was a mixture of amorphous phase and nanograined anatase, which clearly showed strong 〈0 0 1〉 preferred orientation, whereas that at 3 V was completely amorphous. Even without annealing, the MP-20V showed high photocatalytic activities for decomposition of water and methylene blue. In contrast, the anodic TiO2 nanotube film formed in NH4F/ethylene glycol electrolyte revealed photocatalytic activities only after annealing at 723 K, because of the amorphous nature of the as-anodized nanotube film. The MP-20V film also showed superhydrophilicity with UV light irradiation.
Keywords: Anodic TiO2 mesoporous film; Non-annealing procedures; Phosphate/glycerol electrolyte; Photo-induced properties;
Effect of periodic surface cracks on the interfacial fracture of thermal barrier coating system by X.L. Fan; R. Xu; W.X. Zhang; T.J. Wang (9816-9823).
► The effect of multiple surface cracks on interfacial delamination is significant. ► Normalized critical surface crack spacing is an important parameter. ► Steady state does not exist in the case of small surface crack spacing. ► Appropriately high surface crack density can enhance the durability of TBC.Periodic surface cracks and interfacial debonding in thermal barrier coating (TBC) system may be induced during cooling process. The objective of this work is to investigate the effect of periodic surface cracks on the interfacial fracture of TBC system. The finite element method (FEM) incorporating cohesive zone model is used in analysis. It is found that surface crack spacing has significant effect on the initiation and propagation of short interface crack. Three different regions are identified for describing the effect of surface crack spacing. In Region I the interface crack driving force is dramatically reduced due to high surface crack density. In this case, the initiation of interfacial delamination can be delayed. Region II applies as the surface crack spacing is moderate. Analysis of this transition zone brings to the definition of normalized critical surface crack spacing. Region III arises for sufficient large surface crack spacing. In this case, the interface crack driving force reaches a steady state, where the effects of adjacent surface cracks are relatively insignificant and can be ignored. It can be concluded that an appropriately high surface crack density can enhance the durability of TBC system.
Keywords: Surface crack; Delamination; Thermal barrier coating; Energy release rate;
Understanding of gas phase deposition of reactive magnetron sputtered TiO2 thin films and its correlation with bactericidal efficiency by A.B. Panda; S.K. Mahapatra; P.K. Barhai; A.K. Das; I. Banerjee (9824-9831).
► Influence of O2 flow rates on the gas phase plasma during TiO2 film deposition was studied. ► The plasma parameters were determined and correlated with the film properties. ► O2 flow rate affects crystallinity, surface bonding, hydrophilicity, band gap and particle size of TiO2 films. ► These were found to be decisive factors for antibacterial property. ► These were found to be decisive factors for antibacterial property.Nanostructured TiO2 thin films were deposited using RF reactive magnetron sputtering at different O2 flow rates (20, 30, 50 and 60 sccm) and constant RF power of 200 W. In situ investigation of the nucleation and growth of the films was made by Optical Emission Spectroscopy (OES). The nano amorphous nature as revealed from X-ray diffraction (XRD) of the as deposited films and abundance of the Ti3+ surface oxidation states and surface hydroxyl group (OH−) in the films deposited at 50 sccm as determined from X-ray photo electron spectroscopy (XPS) was explained on the basis of emission spectra studies. The increase in band gap and decrease in particle size with O2 flow rate was observed from transmission spectra of UV–vis spectroscopy. Photoinduced hydrophilicity has been studied using Optical Contact Angle (OCA) measurement. The post irradiated films showed improved hydrophilicity. The bactericidal efficiency of these films was investigated taking Escherichia coli as model bacteria. The films deposited at 50 sccm shows better bactericidal activity as revealed from the optical density (OD) measurement. The qualitative analysis of the bactericidal efficiency was depicted from Scanning Electron Microscope images. A correlation between bactericidal efficiency and the deposited film has been established and explained on the basis of nucleation growth, band gap and hydrophilicity of the films.
Keywords: Titanium dioxide; Optical emission spectroscopy; Magnetron sputtering; Bactericidal efficiency;
Electrophoretic deposition of bioactive glass coating on 316L stainless steel and electrochemical behavior study by Mehrad Mehdipour; Abdollah Afshar; Milad Mohebali (9832-9839).
► Bioactive glass (BG) particles were synthesized by a sol–gel process. ► Stable suspension of BG powders in ethanol solvent was prepared. ► Electrophoretic deposition process was used for coating bio active glass particles. ► Electrochemical behavior, cycle polarization and impedance spectroscopy of the composite coating was studied.In this research, submicron bioactive glass (BG) particles were synthesized by a sol–gel process and were then coated on a 316L stainless steel substrate using an electrophoretic deposition (EPD) technique. Stable suspension of bioactive glass powders in ethanol solvent was prepared by addition of triethanol amine (TEA), which increased zeta potential from 16.5 ± 1.6 to 20.3 ± 1.4 (mv). Thickness, structure and electrochemical behavior of the coating were characterized. SEM studies showed that increasing EPD voltage leads to a coating with more agglomerated particles, augmented porosity and micro cracks. The results of Fourier transformed infrared (FTIR) spectroscopy revealed the adsorption of TEA via methyl and amid groups on bioactive glass particles. Presence of bioactive glass coating reduced corrosion current density (i corr) and shifted corrosion potential (E corr) toward more noble values in artificial saliva at room temperature. Percent porosity of the coating measured by potentiodynamic polarization technique increased as EPD voltage was raised. The results of impedance spectroscopic studies demonstrated that the coating acts as a barrier layer in artificial saliva.
Keywords: Electrophoretic; Sol–gel; Electrochemical behavior; Bioactive glass; 316L stainless;
The bioactivity mechanism of magnetron sputtered bioglass thin films by C. Berbecaru; G.E. Stan; S. Pina; D.U. Tulyaganov; J.M.F. Ferreira (9840-9848).
► RF-sputtering: an efficient solution for synthesizing bioactive glass thin films. ► Electrostatic interactions between charged surface and ions from stagnant solution. ► Heterogeneous-type nucleation of apatite from the SBF solution on the glass surface. ► Peculiarities of hydroxyapatite nucleation process and biomineralisation kinetics.Smooth and adherent bioactive coatings with ∼0.5 μm thickness were deposited onto Si substrates by the radiofrequency-magnetron sputtering method at 150 °C under 0.4 Pa of Ar atmosphere using a bioglass powder as target with a composition in the SiO2–CaO–MgO–P2O5–CaF2–B2O3–Na2O system. The bioactivity of the as-prepared bioglass samples was assessed by immersion in simulated body fluid for different periods of time up to 30 days. Grazing incidence X-ray diffraction, Fourier transform infra-red spectrometry and energy dispersive spectroscopy revealed that important structural and compositional changes took place upon immersing the samples in SBF. Whilst the excellent biomineralisation capability of the BG thin films was demonstrated by the in vitro induction of extensive and homogenous crystalline hydroxyapatite in-growths on their surfaces, a series of bioactivity process kinetics peculiarities (derogations from the classical model) were emphasised and thoroughly discussed.
Keywords: Thin films; Bioglass; Sputtering; Infrared spectroscopy; Electron microscopy; Surface properties;
Investigation of the structure of fluoroalkylsilanes deposited on alumina surface by M. Cichomski; K. Kośla; W. Kozłowski; W. Szmaja; J. Balcerski; J. Rogowski; J. Grobelny (9849-9855).
► Preparation of fluoroalkylsilanes on alumina surface by using vapor phase deposition method was investigated. ► Confirmation of presence of modifiers molecules on the Al substrate by XPS, FT-IR and ToF-SIMS measurements was performed. ► Nanotribological studies of fluoroalkylsilanes films with different structure of head group were presented.This paper presents investigation of the structure of fluoroalkylsilanes on alumina surface by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), Fourier transform infrared (FT-IR) spectroscopy and atomic force microscopy (AFM).The fluoroalkylsilanes were prepared on alumina surface using the vapor phase deposition (VPD) method. XPS and ToF-SIMS measurements confirm the presence of fluoroalkylsilanes on the alumina surface. AFM was used to compare the frictional behavior of samples after modifying the alumina surface by fluoroalkylsilanes. Nanotribological studies of fluoroalkylsilanes films with different head groups on the alumina surface include, besides frictional studies, also adhesive forces investigations.It is shown that surface modification of alumina by fluoroalkylsilanes decreases coefficient of friction and adhesive forces values by more than 50% compared to unmodified alumina. In comparison to a non-modified alumina surface all tested silanes, particularly compounds with three reactive atoms in the head group, cause a decrease in the friction coefficients in nanofriction tests. The same effect was also observed for adhesion measurements. It was found that the alumina modified by trifunctional fluoroalkylsilanes have a higher degree of hydrophobicity, lower adhesion, and lower coefficient of friction than the monofunctional fluoroalkylsilanes covered alumina surface.
Keywords: Fluoroalkylsilanes; Nanotribology; Atomic force microscopy; Alumina surface; X-ray photoelectron spectroscopy; Time of flight secondary ion mass spectrometry; Fourier transform infrared spectroscopy;
Microstructure evolution and mechanical properties in VC/SiC nanomultilayers by Yuge Li; Guanqun Li; Duo Yang; Geyang Li (9856-9858).
► VC can serve an excellent job as template materials, and this provides new evidences for the universality of template effect. ► The as-deposited amorphous SiC layers can be crystallized and grow coherently with VC layers even their lattice mismatch reaching 5.3%. ► Multilayers with high hardness can be obtained by proper design of microstructure in nanometer scale.A series of VC/SiC nanomultilayers were synthesized by magnetron sputtering techniques at a substrate temperature of 450 °C. The microstructure and mechanical properties of the multilayers were studied by X-ray diffractometer, high-resolution transmission electron microscopy and nanoindentation device. The results showed that when the SiC layer thickness was below 0.7 nm, the as-deposited amorphous SiC layers were crystallized and grew coherently with VC layers under the template effect of VC layers, accompanied by a remarkable increase in hardness. Further increasing SiC layer thickness, however, the epitaxial growth structure of the multilayers has been disrupted leading to the decrease of hardness.
Keywords: VC/SiC nanomultilayer; Epitaxial growth; Superhardness effect;
Formation of SiO2/polytetrafluoroethylene hybrid superhydrophobic coating by Yansheng Zheng; Yi He; Yongquan Qing; Zhihao Zhuo; Qian Mo (9859-9863).
► The coating showed the water contact angle of 165° and the water sliding angle of 6°. ► The hierarchical structure with the low surface energy leads to surface superhydrophobicity. ► We demonstrated a simple yet efficient approach to preparing superhydrophobic surface.Superhydrophobic coating has been fabricated on the glass substrates with modified SiO2 sol and polytetrafluoroethylene emulsion through a sol–gel process. SiO2 sol was modified with γ-glycidoxypropyl trimethoxysilane. The coatings were characterized by water contact angle measurement, Scanning electron microscope, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and thermal synthetic analysis. The experimental results show that coatings exhibited superhydrophobic and heat-resistant property with a water average contact angle of 156° and sliding angle of 6°, coating has a rough surface with both micro- and nanoscale structures, γ-glycidoxypropyl trimethoxysilane enhanced the hydrophobicity of the coatings. Low surface energy of polymer and special structure of the coatings were responsible for the hydrophobic of the surfaces.
Keywords: Superhydrophobic coating; Micro- and nanoscale structures; Water contact angle; SiO2 sol;
Rapid, simple, and cost-effective treatments to achieve long-term hydrophilic PDMS surfaces by Samu Hemmilä; Juan V. Cauich-Rodríguez; Joose Kreutzer; Pasi Kallio (9864-9875).
Display Omitted► We performed an experimental study investigating 39 PDMS surface treatments. ► Wetting of the surfaces was studied during six months. Also morphology was analyzed. ► Seven coatings supported a contact angle of 30° or less for at least six months. ► Only minutes were needed to prepare a long-term hydrophilic coating. ► Only one biocompatible polymer and oxygen plasma were needed for a treatment.This paper describes rapid, simple, and cost-effective treatments for producing biocompatible and long-term hydrophilic polydimethylsiloxane (PDMS) surfaces identified in an experimental study investigating 39 treatments in all. The wetting of the surfaces was monitored during six months. Changes in surface morphology and chemical composition were also analyzed. Some of the treatments are presented here for the first time, while for earlier presented treatments the selection of investigated parameters was wider and the observation period for the surface wetting longer. The PDMS surfaces were modified by surface activation, physisorption, and synthesis of both “grafting to” and “grafting from” polymer brushes. In surface activation, the PDMS sample was exposed to oxygen plasma, with several combinations of exposure time and RF power. In the physisorption and synthesis of polymer brushes, three commercially available and biocompatible chemicals were used: 2-hydroxyethyl methacrylate (HEMA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP). Thirty-three of the 39 treatments rendered the PDMS hydrophilic, and in 12 cases the hydrophilicity lasted at least six months. Seven of these long-term hydrophilic coatings supported a contact angle of 30° or less. Three of the long-lasting hydrophilic coatings required only minutes to prepare.
Keywords: PDMS; Surface treatment; Hydrophilization; Contact angle; FTIR; SEM;
DFT calculations of the CO adsorption on Mn, Fe, Co, and Au deposited at MgO (1 0 0) and CdO (1 0 0) by Kh.M. Eid; H.O. Taha; M.A. Kamel; A.E. Ashour; W.S. Abdel Halim (9876-9890).
► Adsorption properties of Mn, Fe, Co, and Au atoms adsorbed on various sites of MgO (1 0 0) and CdO (1 0 0) surfaces. ► The characteristics of the CO adsorption on these supported metal atoms. ► This paper provides a detailed account of both geometrical and energetic data as well of the CO/TM/MO surface complexes.Density functional calculations and the embedded cluster model have been utilized to examine the adsorption properties of CO molecules adsorbed on Mn, Fe, Co, and Au atoms deposited on O2−, F, and F+ sites of MgO and CdO terrace surfaces. The adsorption properties of CO have been analyzed with reference to the nature of the oxide support, pairwise and non-pairwise additivity, band gaps, associative adsorption, and electrostatic potentials. CO adsorption on an oxide support is drastically enhanced when CO is adsorbed on a metal deposited on this support. A dramatic change is found, and explained, when one compares the CO binding energy to O2− and F sites. The formation of a strong bond at the support–metal interface has a considerable consequence on the metal–CO binding energy. The binding of CO is dominated by the metal–CO pairwise additive term. While the classical contributions to the electrostatic interactions are quite similar for the deposited metals, they are quite dissimilar when going from defect-free to defect-containing surfaces.
Keywords: DFT; Ab initio; Oxide surfaces; Surface defects; Metal–oxide support; CO; MgO; CdO;
The structural and optoelectronic properties of Ti-doped ZnO thin films prepared by introducing a Cr buffer layer and post-annealing by Y.C. Lin; C.Y. Hsu; S.K. Hung; C.H. Chang; D.C. Wen (9891-9895).
► The effects of buffer layer and annealing on properties of TZO films were studied. ► All films exhibited strong (0 0 2) diffraction peaks of hexagonal structure. ► The buffered TZO films had lower resistivity and higher energy band gap. ► The decrease in resistivity was mainly attributed to increase in Hall mobility. ► Optimal electrical and optical properties were obtained after annealing at 500 °C.This work investigates the effects of Cr buffer layers and post-annealing on the properties of titanium-doped zinc oxide (TZO) thin films prepared by radio frequency magnetron sputter. All films had a (0 0 2) preferential orientation along the c-axis at 2θ ∼ 34°. The crystallinity, grain size, Hall mobility and carrier concentration of TZO films were enhanced by introducing a Cr buffer layer and post-annealing. The decrease in resistivity was mainly attributed to the increase in Hall mobility rather than carrier concentration. As a Cr buffer layer was inserted, the film resistivity decreased by 32% to 5.41 × 10−3 Ω cm while the energy band gap increased from 3.252 to 3.291 eV in comparison with that of the film deposited without the buffer layer. When the Cr-buffered films were annealed in a vacuum, the structural, electrical, and optical properties were improved with increasing annealing temperature. At an annealing temperature of 500 °C, the grain size, resistivity, and energy band gap attained the optimal values of 28.12 nm, 3.37 × 10−3 Ω cm and 3.357 eV, respectively. The average transmittance of TZO films in the visible region was between 75% and 84%, and it decreased with increase in the grain size. The decrease in transmittance is attributed to an increase in surface roughness due to the three-dimensional island grain growth during thermal annealing.
Keywords: Ti-doped ZnO; Buffer layer; Post-annealing; Magnetron sputtering; Electrical resistivity; Transmittance;
Synthesis and properties of Li2SnO3/polyaniline nanocomposites as negative electrode material for lithium-ion batteries by Qiufen Wang; Ying Huang; Juan Miao; Yang Zhao; Yan Wang (9896-9901).
► Li2SnO3/polyaniline nanocomposite (40–50 nm) was synthesized by micro emulsion polymerization. ► Li2SnO3/PANI exhibits lower initial irreversible capacities than Li2SnO3. ► Its capacity retains 569.2 mAh g−1 after 50 cycles.The nanocomposites Li2SnO3/polyaniline (Li2SnO3/PANI) have been synthesized by a micro emulsion polymerization method. The structure, morphology and electrochemical properties of the as-prepared materials are characterized by XRD, FTIR, Raman, XPS, TGA, TEM and electrochemical measurements. Results show that Li2SnO3/PANI nanocomposites are composed of uniform and blocky nano-sized particles (40–50 nm) with clear lattice fringes. Electrochemical measurement suggests that Li2SnO3/PANI exhibits better cycling properties and lower initial irreversible capacities than Li2SnO3 as negative electrodes materials for lithium-ion batteries. At a current density of 60 mA g−1 in the voltage about 0.05–2.0 V, the initial irreversible capacity of Li2SnO3/PANI is 563 mAh g−1 while it is 687.5 mAh g−1 to Li2SnO3. The capacity retained of Li2SnO3/PANI (569.2 mAh g−1) is higher than that of Li2SnO3 (510.2 mAh g−1) after 50 cycles. The PANI in the Li2SnO3/PANI nanocomposites can buffer the released stress caused by the drastic volume variation during the alloying/de-alloying process of Li–Sn.
Keywords: Nanocomposites; Li2SnO3/polyaniline; Micro emulsion polymerization method; Electrochemical properties;
The use of XPS for study of the surface layers of CrNi alloys electrodeposited from the Cr(III) + Ni(II) bath by S. Survilienė; A. Češūnienė; V. Jasulaitienė; I. Jurevičiūtė (9902-9906).
► The morphology of Ni-rich and Cr-rich alloy coatings was found to have a nodular structure, however, Cr-rich deposits had nanoscale cracks. ► The passive film on CrNi alloys consists of Cr(OH)3, Cr(OH)O, Cr2O3 and low amounts of both NiO and organic substances. ► Nickel is incorporated in bulk of CrNi alloys as metallic Ni0, whereas, chromium is present as metallic and carbide phases.This paper reviews the CrNi alloys electrodeposited from Cr(III) oxalate bath containing NiSO4. Ni-rich and Cr-rich alloy coatings were shown to have a nodular structure with smaller size of nodules for the Ni-rich alloy compared to those for the Cr-rich one which has a nanoscale cracked morphology. The chemical composition of the top layers of CrNi alloys electrodeposited from Cr(III) + Ni(II) bath was studied by the X-ray photoelectron spectroscopy method. Analysis of XPS spectra has shown that the surfaces of both Ni-rich and Cr-rich alloys are covered with the oxide films consisting mainly of Cr(OH)3, Cr(OH)O and Cr2O3 with minor amounts of both NiO and organic substances. The data obtained suggest that Cr(OH)3 and Cr(OH)O dominate outside, whereas, Cr2O3 dominates inside the film. It has been found that nickel is incorporated in bulk of the deposits as metallic Ni0, whereas, chromium is present as metallic Cr0 and chromium carbides.
Keywords: CrNi alloys; Morphology; XPS spectra; Chemical composition;
Ti–B–C nanocomposite coatings deposited by magnetron sputtering by J. Lauridsen; N. Nedfors; U. Jansson; J. Jensen; P. Eklund; L. Hultman (9907-9912).
► nc-TiC:B/a-BC x /a-C nanocomposite coatings deposited by magnetron sputtering. ► B is in a solid solution with TiC. ► B induces a rhombohedral distortion of the TiC lattice. ► A contact resistance that is comparable to Ag at loads of ∼1 N.Ti–B–C nanocomposite coatings with a B content of 8–17 at.% have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC:B embedded in a matrix of amorphous (a) C, BC x , TiO x and BO x . The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BC x in coatings with a C/Ti ratio > 1, while the matrix predominantly consists of BC x with some free C in coatings with a C/Ti ratio < 1. nc-TiC:B/a-BC x /a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of ∼1 N against an Au probe, despite the O content of ∼16 at.%.
Keywords: Nanocrystalline; Electron microscopy; Contact resistance; B4C; TiC;
Violet–blue–green emission and shift in Mg-doped ZnO films with different ratios of oxygen to argon gas flow by Haixia Chen; Jijun Ding; Wenge Guo; Feng Shi; Yingfeng Li (9913-9917).
► By magnetron sputtering technique, Mg-doped ZnO films were prepared. ► Crystal structures and surface morphology of Mg-doped ZnO films were discussed. ► Optical properties in Mg-doped ZnO films were systematically investigated. ► Spectral shift of violet–blue emission was discussed in detail.Mg-doped ZnO films were deposited using radio frequency reactive magnetron sputtering at different ratios of oxygen to argon gas flow. The crystal structures, surface morphology and optical properties of Mg-doped ZnO thin films were analyzed. The results indicated that three main emission peaks located at 400, 440 and 483 nm were observed in Mg-doped ZnO films. Violet peak at 400 nm and blue peak centered at 440 nm shifted to 392 nm and 422 nm, respectively, as the ratio of oxygen to argon gas flow is increased. The spectra shift mechanism was discussed, which would be caused by small amount of Zn nanoparticles in Mg-doped ZnO films. The electrons on the Zn conduction band will go across the interface for energy equilibration, and then transition to Zn vacancies and the top of the valence band, which may cause spectra shift.
Keywords: Mg-doped ZnO films; Magnetron sputtering; Surface morphology; Spectral shift;
Layer-by-layer assembly of type I collagen and chondroitin sulfate on aminolyzed PU for potential cartilage tissue engineering application by Xianyun He; Yingjun Wang; Gang Wu (9918-9925).
Display Omitted► A novel biodegradable polyurethane (PU) was successfully synthesized. ► Surface aminolyzing of the PU was performed by reacting it with 1,3-propanediamine. ► Collagen and chondroitin sulfate were deposited alternately on the PU surface.In this paper, a two-step method was used to synthesize a biodegradable polyurethane (PU) composed of l-lysine ethyl ester diisocyanate (LDI), poly(ɛ-caprolactone) diols (PCL-diol) and 1,4:3,6-dianhydro-d-sorbitol (isosorbide). Amino groups were introduced onto the surface of the PU membrane by an amination reacting with 1,3-propanediamine to produce polycationic substratum. And then, type I collagen (Col) and chondroitin sulfate (CS) were deposited alternately on the polycationic substratum through layer-by-layer (LBL) assembly technology. The FTIR and 1H NMR results showed that the polyurethane was successfully synthesized. Rhodamine B isothiocyanate (RBITC) fluorescence spectrum indicated that amino groups were successfully introduced onto the PU surface. The results of quartz-crystal microbalance (QCM) and RBITC-Col fluorescence spectroscopy monitoring the LBL assemble process presented that the Col/CS deposited alternately on the PU surface. X-ray photoelectron spectroscopy (XPS) results displayed that the CS deposited on the PU surface as well. The surface of the assembled PU became even smoother observed from the surface morphology by atomic force microscopy (AFM) imaging. The hydrophilicity of the PU membrane was greatly enhanced though the modification of LBL assembly. The PU modified with the adsorption of Col/CS may be a potential application for cartilage tissue engineering due to its created mimicking chondrogenic environment.
Keywords: PU; Aminolysis; LBL assembly; Type I collagen; Chondroitin sulfate;
Influence of typical defects on thermal conductivity of graphene nanoribbons: An equilibrium molecular dynamics simulation by Dong Yang; Fei Ma; Yunjin Sun; Tingwei Hu; Kewei Xu (9926-9931).
► EMD simulation is performed to study the thermal conductivity of graphene. ► The thermal conductivity depends on the characteristic sizes of GNRs. ► Hydrogen passivation cannot improve but reduce the thermal conductivity. ► It will be further reduced if the there are SW defect arrays involved.The thermal conductivity of defected graphene nanoribbons(GNRs) was studied using equilibrium molecular dynamics simulation. It was demonstrated that the thermal conductivity of GNRs is extremely sensitive to defect configuration. The enhanced scattering at the boundaries will reduce thermal conductivity, the narrower the ribbon is, the stronger the boundary effect is. Hydrogen passivation is exploited to weaken the boundary effect, new scattering mechanisms, however, appears due to sp2-to-sp3 transformation as well as mass difference between hydrogen and carbon. Moreover, Stone–Wales (SW) defects may increase the scattering of phonons and thus reduce thermal conductivity, especially in the case with SW defect arrays perpendicular to the direction of heat flow. Therefore, the defects should be avoided in the fabrication of graphene for good thermal conductivity.
Keywords: Graphene nanoribbons; Defects; Thermal conductivity;
A mechanistic study of H2S adsorption and dissociation on Cu2O(1 1 1) surfaces: Thermochemistry, reaction barrier by Riguang Zhang; Hongyan Liu; Jingrui Li; Lixia Ling; Baojun Wang (9932-9943).
Display Omitted► H2S molecularly adsorbed on perfect and sulfur-containing Cu2O(1 1 1) surfaces. ► Dissociative adsorption of H2S occurs predominantly on oxygen-vacancy surface. ► Vibrational frequencies of adsorbed species can guide experimental IR spectroscopy. ► The presence of surface S atom goes against the H―S bond-breaking of H2S process.The interaction mechanism of H2S with different Cu2O(1 1 1) surfaces, including perfect, oxygen-vacancy and sulfur-containing surfaces, have been systematically studied using periodic density functional calculations. Different kinds of possible modes of H2S, as well as the resultant SH and S species adsorbed on these surfaces are identified. Two types of pathways via molecular and dissociative adsorption processes are mapped out. Our results show that sulfur species (H2S, SH and S) interact with surface Cu centers; H2S exists in the form of molecular adsorption on perfect and sulfur-containing surfaces; the dissociative adsorption of H2S occurs predominantly on oxygen-vacancy surface, suggesting that oxygen-vacancy exhibits a strong catalytic activity toward the dissociation of H2S. On the other hand, the dissociation processes of the molecular and dissociative adsorption H2S, leading to final product S species on these Cu2O(1 1 1) surfaces, show that the overall dissociation process is exothermic. Meanwhile, with respect to molecular adsorption H2S, the activation barrier and reaction energy of the overall dissociation process on perfect and oxygen-vacancy surfaces indicate that H2S can easily dissociate into S species. Importantly, in the case of dissociative adsorption of H2S, the dissociation of H2S into S species is a spontaneous process with respect to molecular adsorption H2S. However, on sulfur-containing surface, the presence of surface S atom goes against the H―S bond-breaking process both thermodynamically and kinetically. Finally, the vibrational frequencies for the adsorbed H2S, SH and S species on these surfaces have been obtained, which can be applied to guide surface vibrational spectroscopy in experiment.
Keywords: H2S; Cu2O(1 1 1); Adsorption; Dissociation; Density functional theory;
Unusual pattern formation on Si(1 0 0) due to low energy ion bombardment by Tanmoy Basu; Jyoti Ranjan Mohanty; T. Som (9944-9948).
► An angular window of 65–82.5°, in terms of ion incident angle, was chosen for this study. ► Parallel-mode ripple formation is observed in the angular window of 65–67°. whereas unusual patterns evolve over the angular window of 70–77.5°. ► Perpendicular mode ripples are formed at an incident angle of 80°. ► We showed that the transition from parallel- to perpendicular-mode ripples is not a sharp one. ► The observed patterns are attributed to surface confined viscous flow and sputter erosion under ion bombardment.In this paper evolution of silicon surface topography, under low energy ion bombardment, is investigated at higher oblique incident angles in the range of 63–83°. Si(1 0 0) substrates were exposed to 500 eV argon ions. Different surface morphologies evolve with increasing angle of incidence. Parallel-mode ripples are observed up to 67° which undergo a transition to perpendicular-mode ripples at 80°. However, this transition is not a sharp one since it undergoes a series of unusual pattern formation at intermediate angles. For instance, mounds, cone-, and needle-like structures appear at intermediate angles, viz. in the angular range of 70–78°. Complete smoothening of the silicon surface is observed at incident angles beyond 80°. The observed patterns are attributed to surface confined viscous flow and sputter erosion under ion bombardment.
Keywords: Silicon; Ion beam sputtering; Surface confined viscous flow and sputter erosion; Atomic force microscopy;
Morphological study of PLD grown CuO films on SrTiO3, sapphire, quartz and MgO substrates by M. Kawwam; F. Alharbi; A. Aldwayyan; K. Lebbou (9949-9953).
► Cupric oxide films were prepared on various substrates by the pulsed laser deposition (PLD) technique to investigate their effects on surface morphology. ► A decrease in the average surface roughness was recorded as the substrate temperature decreased. ► Deposition at low pressures produced greater surface roughness, while higher oxygen pressure under an adjusted target–substrate distance produced smaller crystallites and a smoother film surface. ► Reducing the laser energy density led to lower densities and smaller micro-liquid droplets formed on the surfaces. ► The discussed results could be useful for better understanding the effect of PLD parameters control on CuO film morphology. It could also serve as a reference for the fabrication of CuO-based devices, in which the surface quality of the CuO films is highly important.Cupric oxide (CuO) films were prepared on various substrates by the pulsed laser deposition (PLD) technique to investigate their effects on surface morphology. As the substrate temperature decreased, the film surface roughness was also observed to decrease. This trend was also correlated with the polycrystalline structure of the films. Deposition at low pressures produced greater surface roughness because larger crystallites emerged from the surface, while higher oxygen pressure under an adjusted target–substrate distance produced smaller crystallites and a smoother film surface. Reducing the laser energy density led to lower densities and smaller micro-liquid droplets formed on the surfaces. The presented results could be useful for better understanding the effect of process parameters control on CuO film morphology. It could also serve as a reference for the fabrication of CuO-based devices, in which the surface quality of the CuO films is highly important.
Keywords: Thin film morphology; CuO; Pulsed laser deposition; Surface roughness;
Comparative study on the effects of different annealing conditions on the surface morphology, crystallinity, and optical properties of ZnO micro/nanoparticle-based discs by Rabab Khalid Sendi; Shahrom Mahmud (9954-9960).
► High-density zinc oxide discs were prepared using ZnO micro- and nanoparticles. ► Unique secondary growth in ZnO nanoparticles and multilayer grains were observed. ► Annealing can be employed as a new technique for controlling the ZnO properties.The effects of annealing parameters on the surface morphology, crystallinity, and optical properties of ZnO disc were investigated. Variations in the annealing temperatures and gas flow rates were found to have a profound impact; grain growth was enhanced even at the low annealing temperature of only 400 °C. SEM and AFM revealed smooth and uniform grain growth after annealing treatment, especially at 800 °C. A unique secondary growth of ZnO nanoparticles and multilayer grain growth that have not been reported elsewhere were also observed. The annealing treatment was also found to improve grain crystallinity as illustrated by the lowering of intrinsic compressive stress based on the XRD lattice constant and FWHM data. The PL spectra of the M-Disc showed a huge band edge emission at 371–376 nm. In contrast, the N-Disc exhibited a dominant and broad visible PL emission in the green band with peaks at 519–533 nm. These peaks were attributed to a very high concentration of structural defects (oxygen vacancies and zinc/oxygen interstitials). The annealing conditions had a significant effect on the properties of ZnO. Increased percentage of oxygen in the O/Ar from 50% to 100% did not change the M-Disc spectra. However, the XRD pattern of the N-Disc revealed that the (0 0 2) peak intensity decreased, the position of the (1 0 1) peak slightly shifted toward a higher angle, and the FWHM of the (1 0 1) peak improved. The experimental results showed that thermal annealing could enhance the different properties of ZnO discs.
Keywords: Annealing; Sintering; Scanning electron microscopy (SEM); Optical properties;
Surface morphology of magnesium alloy irradiated by high-intensity pulsed ion beam by P. Li; T.X. Peng (9961-9968).
► Three groups of magnesium alloys with different initial surface roughness were prepared. ► Surface morphology of magnesium alloy irradiated by HIPIB was investigated. ► Crater formation and wavy feature strongly depends on the initial surface roughness. ► Initial surface roughness affects the evolution of R a with shot number. ► S m monotonely increases as the shot number increases.Surface morphology of magnesium alloy irradiated by high-intensity pulsed ion beam (HIPIB) at energy density of 1.1–3.4 J/cm2 with shot number from one to ten has been investigated by using scanning electron microscope and profilometer in order to explore the interaction mechanism between HIPIB and metallic materials. Three groups of samples with different initial surface roughness (R a) were prepared to determine the effect of surface state on surface morphology. It was found that for the medium-roughness and high-roughness samples the irradiated surface represents a wavy feature and the formation of crater in local region due to selective ablation of the microprotrusions deriving from the rougher initial surface, however, no obvious craters were observed for the low-roughness sample, which exhibited texture feature and relatively mild irradiation damage. The mean spacing of surface profile irregularities (S m) increases as shot number increases for various initial surface roughness samples. For low-roughness and medium-roughness samples R a increases with increasing shot number, whereas R a first increases slightly, and then decreases with increasing shot number for the high-roughness sample. It is also demonstrated that increasing energy density led to the increase in both R a and S m at all the shot number investigated, and the corresponding surface morphology altered from obvious craters at the lower energy density of 1.1 J/cm2 to distinct droplet ejection feature owing to more intense energy deposition at the higher energy density of 2.3 and 3.4 J/cm2.
Keywords: Magnesium alloy; High-intensity pulsed ion beam; Surface morphology; Roughness;
Structural, optoelectronic, luminescence and thermal properties of Ga-doped zinc oxide thin films by S.S. Shinde; P.S. Shinde; Y.W. Oh; D. Haranath; C.H. Bhosale; K.Y. Rajpure (9969-9976).
► The ecofriendly deposition of Ga-doped zinc oxide. ► Influence of Ga doping onto physicochemical properties in aqueous media. ► Electron–phonon coupling by Raman. ► Chemical bonding structure and valence band analysis by XPS.Ga-doped ZnO thin films are synthesized by chemical spray pyrolysis onto corning glass substrates in aqueous media. The influence of gallium doping on to the photoelectrochemical, structural, Raman, XPS, morphological, optical, electrical, photoluminescence and thermal properties have been investigated in order to achieve good quality films. X-ray diffraction study depicts the films are polycrystalline and fit well with hexagonal (wurtzite) crystal structure with strong orientations along the (0 0 2) and (1 0 1) planes. Presence of E 2 high mode in Raman spectra indicates that the gallium doping does not change the wurtzite structure. The coupling strength between electron and LO phonon has experimentally estimated. In order to understand the chemical bonding structure and electronic states of the Ga-doped ZnO thin films XPS analysis have been studied. SEM images shows the films are adherent, compact, densely packed with hexagonal flakes and spherical grains. Optical transmittance and reflectance measurements have been carried out. Room temperature PL spectra depict violet, blue and green emission in deposited films. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in these polycrystalline films.
Keywords: Ga:ZnO thin films; Raman; XPS; Morphological; Optoelectrical;
The austenite/ɛ martensite interface: A first-principles investigation of the fcc Fe(1 1 1)/hcp Fe(0 0 0 1) system by Seung-Joon Lee; Young-Kook Lee; Aloysius Soon (9977-9981).
Display Omitted► First-principles calculation of paramagnetic iron surfaces and interfaces. ► Zero-temperature interfacial energy of non-magnetic fcc Fe(1 1 1)/hcp Fe(0 0 0 1) converges to a negative value. ► Dominant chemical bonding at iron interface as determined from electronic structure analysis.Based on first-principles density-functional theory, we study the surface energetics and its electronic structure of fcc Fe(1 1 1) and hcp Fe(0 0 0 1), as well as the interfacial properties of the fcc Fe(1 1 1)/hcp Fe(0 0 0 1) system. Interestingly, we find the zero-temperature interfacial energy of this system to be negative, largely accounted for by chemical bonding at this interface. Consequently, this study provides an initial platform for the fundamental understanding of iron interfaces which is closely related to the stacking fault energy in iron alloys.
Keywords: Density-functional theory (DFT); Thermodynamics; Iron surfaces; Stacking fault energy (SFE); Interfacial energy; Twinning-induced plasticity (TWIP) steels;
Effect of nitrogen ion implantation on corrosion inhibition of nickel coated 316 stainless steel and correlation with nano-structure by Ali-Reza Grayeli-Korpi; Hadi Savaloni (9982-9988).
► Enhancement of corrosion resistance of stainless steel by nickel nitride coating. ► Correlation between the structural analyses and the potentiodynamic results is achieved. ► Optimum corrosion result is achieved for critical surface roughness and N+ ion fluence.The influence of implantation of N+ with 20 keV energy and different fluences in the range of 1 × 1017 and 5 × 1018 ions/cm2 in the nickel coated type 316 stainless steel (SS) on the corrosion inhibition of SS in 3.5 wt% NaCl solution is investigated. The highest available N+ fluence showed highest corrosion inhibition. X-ray diffraction (XRD) analysis showed formation of nickel nitride phases that enhanced by increasing the N+ fluence. Surface morphology was studied by atomic force microscope (AFM) and scanning electron microscope (SEM) before and after corrosion test, respectively. AFM results showed that by increasing N+ fluence surface of the sample becomes smoother that may be the result of heat accumulation during implantation causing higher rate of diffusion in the sample.
Keywords: Ion implantation; Stainless steel; Corrosion; Ni thin film;
Novel polypyrrole-sensitized hollow TiO2/fly ash cenospheres: Synthesis, characterization, and photocatalytic ability under visible light by Bing Wang; Chuang Li; Jianfeng Pang; Xutang Qing; Jianping Zhai; Qin Li (9989-9996).
► The threshold of PPy–TiO2/FAC can reach 560 nm, and it can take advantage of solar light. ► These fresh photocatalysts can be easily separated from water due to their buoyant property. ► The photocatalysts retained their photocatalytic ability after several reaction cycles. ► A new way of reuse of fly ash is mentioned in this research.The polypyrrole-sensitized TiO2 layer on fly ash cenosphere (PPy–TiO2/FAC) was successfully prepared as a promising photocatalyst with visible light response. Photocatalytic activity and kinetics of PPy–TiO2/FAC under visible light were detected in details from aspects of different dopant concentration of HCl and different pyrrole (Py)/Ti molar ratio by detecting photodegradation of methylene blue (MB) and phenol, respectively. It was found that the decomposition rate increased with the increasing Py/Ti molar ratio up to an optimal value, beyond which the photocatalytic activity showed a decreasing tendency. The concentration of HCl in the preparation of PPy–TiO2/FAC also largely influenced the photodecomposition rate of target contamination. The results demonstrate that when the molar ratio of Py/Ti is 1% and the concentration of HCl is 1 mol L−1, the synthesized photocatalyst showed the best photocatalytic activity under visible light.
Keywords: Polypyrrole; TiO2; Fly ash cenosphere; Photocatalysis;
Investigation of the presence of metal droplets after pulsed InN and GaN epitaxial growth using atomic force microscopy and nanoindentation by Penka T. Terziyska; Kenneth Scott Alexander Butcher; Dimiter Alexandrov (9997-10001).
► GaN and InN layers are grown by pulsed migration enhanced epitaxial growth. ► Presence of Ga- and In-metal droplets is identified by nanoindentation. ► The method is confirmed for In-droplets on InN layers by XRD and etching with HCl. ► AFM phase-contrast does not conform to the surface material distribution.
Keywords: AFM; Force–distance curves; Phase-contrast; InN; GaN;
Synthesis of high-surface-area γ-Al2O3 from aluminum scrap and its use for the adsorption of metals: Pb(II), Cd(II) and Zn(II) by Yvan J.O. Asencios; María R. Sun-Kou (10002-10011).
Display Omitted► Aluminum hydroxide obtained from aluminum scrap led to the formation of gamma alumina. ► Acidic pH of precipitation favored the formation of small particles of high surface areas. ► Higher aging temperature favored the formation of large structures of large pore sizes. ► Higher aging temperature generated symmetrical solids of regular hexagonal prism forms. ► Aluminas of large pores adsorbed metals as following: Pb (1.75 Å) > Cd (1.54 Å) > Zn (1.38 Å).Several types of alumina were synthesized from sodium aluminate (NaAlO2) by precipitation with sulfuric acid (H2SO4) and subsequently calcination at 500 °C to obtain γ-Al2O3. The precursor aluminate was derived from aluminum scrap. The various γ-Al2O3 synthesized were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), adsorption–desorption of N2 (S BET) and scanning electron microscopy (SEM). XRD revealed that distinct phases of Al2O3 were formed during thermal treatment. Moreover, it was observed that conditions of synthesis (pH, aging time and temperature) strongly affect the physicochemical properties of the alumina. A high-surface-area alumina (371 m2 g−1) was synthesized under mild conditions, from inexpensive raw materials. These aluminas were tested for the adsorption of Cd(II), Zn(II) and Pb(II) from aqueous solution at toxic metal concentrations, and isotherms were determined.
Keywords: Gamma alumina; Adsorbent; Adsorption; Zinc; Cadmium; Lead;
Effect of hydrogen peroxide treatment on the properties of wool fabric by Xin Wang; Xiaolin Shen; Weilin Xu (10012-10016).
► Hydrogen peroxide treatment was applied to improve the surface wettability, moisture transfer properties and other related properties of wool fabric. ► The tip of wool scale was smoothened and parts of the scale were peeled off after hydrogen peroxide treatment. ► The water absorbing time could be decreased to less than 1 s and the wicking properties of wool fabrics were dramatically improved after hydrogen peroxide treatment. ► Fabric showed better shrinkproof property and whiteness level after treatment.In this study, hydrogen peroxide treatment was applied to improve the surface wettability, moisture transfer properties and other related properties of wool fabric. SEM images showed the tip of wool scale was smoothened and parts of the scale were peeled off after hydrogen peroxide treatment. The time for a water droplet to sink into the fabric could decrease to less than 1 s and the wicking properties of wool fabrics were dramatically improved after hydrogen peroxide treatment. Shrinkage and whiteness of the fabric were improved due to the modification of scale and the bleaching effect of hydrogen peroxide, respectively. The fabrics became weaker and ductile with less than 4% weight loss. This study would benefit further application of wool fiber in summer clothing in which the surface wettability and moisture transfer properties are essential and determinative.
Keywords: Wool; Hydrogen peroxide; Surface wettability; Clothing;
Formation of microarc oxidation coatings on magnesium alloy with photocatalytic performance by Weiping Li; Mingqi Tang; Liqun Zhu; Huicong Liu (10017-10021).
► TiO2 nanoparticles of electrolyte affect the MAO coatings significantly. ► TiO2 nanoparticles change the MAO coating from gray to blue. ► The blue MAO coating contains anatase TiO2 and rutile TiO2. ► The blue MAO coating performs certain photocatalytic performance.Microarc oxidation (MAO) coatings were prepared on AZ91D magnesium alloy in a phosphate electrolyte with and without TiO2 nanoparticles. The effect of TiO2 nanoparticles in the electrolyte on the thickness, surface morphology, composition, structure, corrosion resistance and photocatalytic performance of the coatings were investigated. The appearance and structure of the coatings changed significantly after the TiO2 nanoparticles were added into the electrolyte. The coatings produced in the phosphate electrolyte displayed a grayish white appearance and were mainly composed of MgO and Mg3(PO4)2. However, the coatings formed in the electrolyte with various TiO2 nanoparticles had a blueish color and, additionally, contained the rutile TiO2 and Mg2TiO4. The results of corrosion and photocatalytic measurements show that the coatings formed in the electrolyte with TiO2 nanoparticles not only provided better corrosion protection for magnesium alloy but also exhibited photocatalytic properties.
Keywords: Magnesium alloy; Oxidation; TiO2 Nanoparticles; Corrosion; Photocatalytic;
Synergetic effect of ZrO2 on the oxidation–reduction reaction of Fe2O3 during chemical looping combustion by Qinliang Tan; Wu Qin; Qiuluan Chen; Changqing Dong; Wenyan Li; Yongping Yang (10022-10027).
► Properties of Fe2O3/ZrO2 composite. ► Adsorption of CO and O2 on Fe2O3/ZrO2 composite. ► Mechanisms of CO oxidation by Fe2O3 related to the fuel reactor of the CLC system. ► Mechanisms of Fe2O2 oxidation by O2 related to the air reactor of the CLC system.Fe2O3/ZrO2 model oxygen carrier is constructed at atomic-level precision under ultra-high-vacuum conditions. Based on density functional theory calculations and molecular dynamical simulations, structure and energy analysis suggests that the complex Fe2O3/ZrO2 is stable and more chemically active than the pure Fe2O3, ZrO2 promotes the adsorption of CO, which is chemisorption rather than physisorption on the pure Fe2O3 surface. Interface electronic interaction of Fe2O3/ZrO2 makes Fe2O3 positive to accept electron from CO easily and hence promoting the chemisorption of CO and the formation of carbonate species, while such electronic interaction makes it relatively more difficult in oxidizing Fe2O2 supported on ZrO2. However, all reaction barrier energies are small enough for Fe2O2 oxidation to happen under high temperature in the CLC system. Both CO oxidation by Fe2O3/ZrO2 related to the fuel reactor in the chemical looping combustion (CLC) system and Fe2O2/ZrO2 oxidation by O2 related to the air reactor in CLC system illustrate the synergetic effect of ZrO2 on the CO oxidation and Fe2O2 oxidation.
Keywords: Chemical-looping combustion; Fe2O3; ZrO2; CO; Density functional theory;
Microplasma synthesis on aluminum with additions of iron and nickel soluble complexes in electrolyte by A.B. Rogov; I.V. Mironov; O.P. Terleeva; A.I. Slonova (10028-10033).
► Alkaline homogeneous electrolyte with transition metals complexes. ► Coatings contain metallic iron, nickel and their oxides in alumina–silica matrix. ► Effect of Fe/Ni ratio on coatings properties and process characteristics.The microplasma synthesis of coatings containing iron and nickel from homogeneous electrolytes has been studied. For stabilization of transition metals in solution, it is proposed to use chelation. It was found that the synthesis of coatings using alternating current leads to the formation of metallic iron and nickel particles in addition to oxide phases. The iron and nickel complexes concentrations ratio in the electrolyte correlates with the coatings composition. Obtained coatings have been studied by scanning electron microscopy with X-ray microanalyser and by X-ray diffraction with Cu and Mo radiation. The metal content in the coating was determined spectrophotometrically from the absorption of iron thiocyanate complexes and nickel dimethylglyoxime complex.
Keywords: Microplasma process; EDTA complexes; Homogeneous electrolyte; Nickel; Iron;
Preparation of Fe-doped TiO2 nanoparticles immobilized on polyamide fabric by Hui Zhang; Hong Zhu (10034-10041).
Display Omitted► We used a facile method to immobilize the Fe-doped TiO2 nanoparticles on the surface of polyamide fiber. ► We prepared the Fe-doped TiO2-coated polyamide fabric with the higher photocatalytic activity. ► We characterized the fiber using SEM, TEM, XRD, XPS, DSC and TG techniques. ► The hydrothermal process may be suitable for the potential applications.A thin layer of nano-scaled Fe-doped TiO2 particles prepared by hydrothermal method is immobilized on the surface of polyamide 6 (PA6) fiber using tetrabutyl titanate as the precursor, ferric trichloride as the doping agent and chitosan as the dispersant agent. The morphology, crystal structure, thermal behavior, composition and chemical structure of PA6 fabric before and after treatments are characterized by means of scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, differential scanning calorimetry and thermal gravimetric analysis techniques. The properties of diffuse reflectance spectrum, tensile, air permeability, whiteness, yellowness and photocatalytic activity are also analyzed. It is found that the anatase phase Fe-doped TiO2 nanoparticles with crystal size of 12 nm or so are synthesized, and simultaneously grafted onto the fiber surface during the processing. Compared with the TiO2-coated fabric, the thermal stability of the Fe-doped TiO2-coated fabric changes a little. The absorption ability to ultraviolet (UV) rays and visible light is greatly improved. The breaking force and breaking elongation increase to some extent because of the shrinkage of fabric. The air permeability decreases distinctly. The color of PA6 fabric changes from white to light brownish because of the introduction of ferric trichloride. The photocatalytic activity of methylene blue decolorization is enhanced under sunlight and UV irradiation.
Keywords: Polyamide 6; Fe-doped TiO2 nanoparticle; Hydrothermal method;
Scalable patterning on shape memory alloy by laser shock assisted direct imprinting by Chang Ye; Gary J. Cheng (10042-10046).
Laser shock assisted direct imprinting. Dislocation structure after laser shock two way shape memory effects.Display Omitted► An imprinting technique called laser shock assisted direct imprinting (LSADI) is reported, which can generate patterned indents in metallic surface without heating or etching. ► This method can be applied to any metallic surface and the patterns generated can be adjusted by changing the pattering of mask. ► This method can be easily scaled up for mass production, and it brings beneficial environmental impact since no chemicals are involved. ► LSADI has been applied to NiTi SMA in order to generate two-way shape memory effects.In this study, patterned microindents are generated on the surface of NiTi shape memory alloy by laser shock assisted direct imprinting (LSADI). During LSADI, the plasma pressure generated by the laser pulse punches the mask into the target material and thus generates patterned indents. It has been demonstrated that thermally controllable surface pattern can be generated on NiTi surface through LSADI. Compared to traditional imprinting techniques, LSADI does not require a sharp mold, nor does it involve any heating or etching process. More importantly, it can be used to pattern metals. It is scalable and can be potentially used in treating functional metallic components for advanced applications.
Keywords: Laser shock indentation; Direct imprinting; Shape memory alloy;
Microwave absorption properties of CeO2 and Zn-modified CeO2 microstructures by Hongjing Wu; Liuding Wang; Yiming Wang; Shaoli Guo (10047-10052).
Display Omitted► Morphology-controlled CeZn and CeO2 were synthesized by a facial method. ► Microwave-absorbing properties of CeZn and CeO2 were firstly investigated. ► A minimal RL of −34 dB was obtained for CeZn solid with 2.0 mm thickness layer. ► This could be attributed to their unique structure properties and geometric effects.CeO2 and Zn-modified CeO2 microstructures have been synthesized by a facile hydrothermal method and their microwave absorption properties have been investigated in detail. Complex permittivity and permeability of CeO2 and CeZn paraffin composites have been measured over the range of 2–18 GHz. Excellent microwave absorption properties have been obtained for CeO2 and CeZn microstructures compared with ZnO nanoparticles. Especially, maximum RL increases with increasing the concentration of CeZn microspheres in the composites and minimal RL value is −35 dB with 70 wt.% CeZn microspheres at 2.0 mm thickness. This phenomenon is attributed to both unique structure properties and geometric effect of CeO2 and CeZn microstructures.
Keywords: Coating; CeO2; Zn-modified CeO2; Microwave absorption; Defects;
Bonding of Cf/SiC composite to Invar alloy using an active cement, Ag–Cu eutectic and Cu interlayer by Zhao Lei; Li Xiaohong; Hou Jinbao; Sun Qiang; Zhang Fuli (10053-10057).
► Selfmade active cement, Ag–Cu eutectic alloy and pure Cu foils were used for joining Cf/SiC composite and Invar alloy. ► We have revealed the interface structure of the joint. ► The effects of brazing parameters on the microstructure of the Cf/SiC composites/Invar alloy joint are analyzed. ► The optimum brazing process for joining Cf/SiC composite and Invar alloy has been determined.The interfacial microstructures and mechanical properties of the joints formed by active cement added brazing in vacuum of Cf/SiC composite to Invar alloy, using Ag–Cu eutectic alloy and pure copper foil as braze alloy and interlayer respectively, were investigated. CuTi, Cu4Ti3, Fe2Ti and the reaction layer of TiC and Si were the predominant components at the joint interface. The maximum shear strength of the joint was 77 MPa for brazing at 850 °C for 15 min. The results show that active cement added brazing in vacuum using Ag–Cu eutectic alloy and Cu interlayer can be used successfully for joining Cf/SiC composites to Invar alloy.
Keywords: Composites; Ferrous metals and alloys; Bonding;
Bactericidal behavior of Cu-containing stainless steel surfaces by Xiangyu Zhang; Xiaobo Huang; Yong Ma; Naiming Lin; Ailan Fan; Bin Tang (10058-10063).
► Cu-containing stainless steel (Cu-SS and CuNi-SS) surfaces were prepared. ► Cu-SS exhibits a much stronger bactericidal activity than CuNi-SS. ► Cu ions were released from the Cu-SS surfaces. ► Cu ions action with cell membranes, resulting in bacterial death. ► Bacterial exposure to Cu-SS surfaces for short time did not result in DNA damage.Stainless steels are one of the most common materials used in health care environments. However, the lack of antibacterial advantage has limited their use in practical application. In this paper, antibacterial stainless steel surfaces with different Cu contents have been prepared by plasma surface alloying technology (PSAT). The steel surface with Cu content 90 wt.% (Cu-SS) exhibits strong bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) within 3 h. Although the Cu-containing surface with Cu content 2.5 wt.% (CuNi-SS) can also kill all tested bacteria, this process needs 12 h. SEM observation of the bacterial morphology and an agarose gel electrophoresis were performed to study the antibacterial mechanism of Cu-containing stainless steel surfaces against E. coli. The results indicated that Cu ions are released when the Cu-containing surfaces are in contact with bacterial and disrupt the cell membranes, killing the bacteria. The toxicity of Cu-alloyed surfaces does not cause damage to the bacterial DNA. These results provide a scientific explanation for the antimicrobial applications of Cu-containing stainless steel. The surfaces with different antibacterial abilities could be used as hygienic surfaces in healthcare-associated settings according to the diverse requirement of bactericidal activities.
Keywords: Stainless steel; Cu-containing surfaces; Antibacterial mechanism; DNA; Morphological changes;
Annealing effects on properties of Ag–N dual-doped ZnO films by Li Duan; Wenxue Zhang; Xiaochen Yu; Ziqiang Jiang; Lijun Luan; Yongnan Chen; Donglin Li (10064-10067).
► The influence of post-annealing conditions on the properties of p-type ZnO:(Ag,N) films was investigated. ► Transition from n-type to p-type conduction occurred at the annealing temperature of 400 °C. ► The hole concentration first increases and then decreases with increasing annealing temperature. The optimum annealing temperature is about 500 °C. ► The ZnO:(Ag,N) films exhibit a strong ultraviolet emission after annealing in O2.Ag–N dual-doped p-type ZnO (ZnO:(Ag,N)) thin films have been prepared using the sol–gel method. The modifications of the structural, electrical and optical properties of ZnO:(Ag,N) films after annealing in various atmosphere in the temperature range of 300–600 °C are discussed. Results show the oxygen-rich environment is benefit to the p-type samples. Transition from n-type to p-type conduction occurred at the annealing temperature of 400 °C. The optimum annealing temperature is about 500 °C.
Keywords: ZnO; Dual-doping; Post-annealing; Sol–gel method;
Synthesis of hollow nanosphere Sb2Te3 via a thermal evaporation process by Guling Zhang; Yujie Liang; Honglong Shi; Bin Zou; Jiapeng Wu; Pan Zhao; Wanjun Bai; Huan Yang; Wenzhong Wang (10068-10071).
► The hollow nanosphere antimony telluride was firstly fabricated. ► The average size of nano-Sb2Te3 is about 50–80 nm. ► The precipitation of Te from Sb2Te3 was observed in Raman spectra. ► The NaCl drops acted as absorption substrates for Sb2Te3 molecules.Hollow nanosphere antimony telluride (nano-Sb2Te3) was fabricated with antimony (Sb) and telluride (Te) vapors via a fast and facile a thermal evaporation process. The average size of nano-Sb2Te3 is about 50–80 nm with the wall thickness of about 10 nm. XRD test indicates that the as-prepared Sb2Te3 hollow nanospheres are well crystallized. And Raman studies show the precipitation of Te from Sb2Te3 under a relative high laser power. The present study offers a fast way for synthesis of nanostructure compounds, which may have scientific and technological applications in various fields.
Keywords: Antimony telluride; Hollow nanosphere; Thermal evaporation;
Influence of seawater and its aerosols on copper patina composition by L. Veleva; W. Farro (10072-10076).
► Copper patina was grown during one-year period on samples exposed to splash, tidal, full immersion sea zone and atmospheric aerosols. ► The cuprite and atacamite contributed most to patina formation. ► Atacamite became the sole majority phase in the full immersion zone. ► Cuprite decreased over time and posnjakite and chalcanthite appeared as minority phases. ► Copper patina composition is strongly influenced by chloride pollution and specific zone conditions.X-ray diffraction analysis was used to monitor patina composition on copper samples exposed during one-year period to different seawater zones (splash, tidal and full immersion) and marine atmospheric aerosols. Two phases contributed most to patina formation: cuprite (copper oxide) and atacamite (copper chloride compound). Their relative XRD spectra intensities were very similar in patina formed in the tidal sea zone, but atacamite became the sole majority phase in the full immersion zone. The cuprite phase decreased over time, and two minority copper sulfates phases appeared: posnjakite and chalcanthite (CuSO4). The results revealed that copper patina composition is strongly influenced by chloride pollution and specific zone conditions. Additional factors, such as wind-blown sand, continuous dredging in coastal areas and vessel docking, influenced degree of pollutant compound adherence to patinas and consequently their structure (porous or compact).
Keywords: Copper patina; XRD; Seawater; Atmospheric marine aerosols;
High-resolution XPS spectromicroscopy study of micro-patterned gold–tin surfaces by O. Renault; A. Garnier; J. Morin; N. Gambacorti; F. Bertin (10077-10083).
► Surface chemical-state analysis of gold–tin micro-patterns obtained after partial delamination of photo-resist during tin deposition. ► Heterogeneity of gold–tin surface chemistry (metal, oxide and alloyed, eutectic phase) over 10 μm. ► Practical use of high-resolution core level XPS spectromicroscopy (1 μm lateral resolution).We report on high-resolution chemical state mapping performed with a laboratory, spectroscopic X-ray photoelectron emission microscope (XPEEM) on electro-deposited gold–tin patterns (100 μm × 20 μm) for packaging applications of micro-systems. The analysis conditions were selected to achieve a lateral resolution below 1 μm and an energy resolution of 0.8 eV for Au4f 7/2 and Sn3d 5/2 for images acquired over 5 min. The chemical state maps reveal the non-uniformity of the gold/tin chemistry over regions of typical width of less than 10 μm. More precisely, the coexistence of Au and AuSn4 states, and the heterogeneity of Sn oxidation were shown. The results evidence the role of the partial delamination of the photo-resist during the electro-deposition of tin due to degraded adhesion properties on gold. These conclusions are drawn from direct inspection of the raw image data sets, and are supported by statistical treatments using Principal Component Analysis (PCA). This is a clear example of the interest in using high resolution XPS imaging by XPEEM at a practical level in applied surface science, and its complementarity to other surface imaging techniques.
Keywords: Patterning; XPS; Spectromicroscopy; XPEEM; Lateral resolution; Adhesion;
Facile preparation of sol–gel-derived ultrathin and high-dielectric zirconia films for capacitor devices by Hsin-Chiang You; Chun-Ming Chang; Tzeng-Feng Liu; Chih-Chia Cheng; Feng-Chih Chang; Fu-Hsiang Ko (10084-10088).
► Zirconia ultrathin film from the sol–gel solution is fabricated. ► Out-gassing behavior of the sol–gel-derived thin film is evaluated. ► The dielectric constant is dependent on the retention effect of preparation solvents.This study successfully prepared zirconia ultrathin films from the sol–gel solution with dispersion of zirconium halide in 1-octanol solvent. The film was subjected to annealing treatments after sol–gel spin-coating, and the films of interest were evaluated. The amorphous morphology of the zirconia film was identified using high-resolution transmission electron microscopy and X-ray diffractometry. The plot of the current density with respect to the electric field demonstrates that the as-deposited film at 500 °C annealing exhibited an inferior leakage current, whereas 600 °C annealing stabilized the film with a satisfactory leakage current of 10−8 to 10–9 A/cm2. The out-gassing behavior of the sol–gel-derived thin film was evaluated using a thermal desorption system, that is, atmospheric pressure ionization mass spectrometry. The dielectric constant of the film was dependent on the retention effect of the preparation solvents. The low residual solvent for the preparation of the thin film with 1-octanol solvent and 600 °C annealing contributed to the superior high-k property.
Keywords: Zirconia ultrathin film; Sol–gel; High dielectric material; Out-gassing contamination;
Colouration process of colloidal tungsten oxide nanoparticles in the presence of hydrogen gas by N. Tahmasebi Garavand; M. Ranjbar; S.M. Mahdavi; A. Iraji zad (10089-10094).
Display Omitted► Tungsten oxide nanoparticles were prepared by pulsed laser ablation (PLA). ► Hydrogen catalyst (Pd) was deposited on tungsten oxide nanoparticles surface. ► After exposing the colloidal nanoparticles to hydrogen gas coloration occurs. ► An absorption peaks (1.6 eV) appeared at the initial moments of hydrogen exposing. ► Two other peaks (1.26, 1.97 eV) become dominant at long hydrogen exposure times.In this study, tungsten oxide nanoparticles were fabricated by pulsed laser ablation (PLA) of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.2 g/lit PdCl2 solution was added to activate the solution against the hydrogen gas. Dynamic light scattering and X-ray photoelectron spectroscopy were used to measure the average size and the surface chemical composition of the synthesized nanoparticles, respectively. The aim is to investigate the influence of hydrogen exposure time on colouration process of colloidal nanoparticles. According to optical measurements, hydrogen bubbling into the produced colloidal Pd–WO3 led to formation of several absorption peaks at ∼1.26, ∼1.6 and ∼1.97 eV. We observed the appearance and growth of a peak at 1.6 eV at the initial stages of hydrogen exposure. However, two other peaks became dominant at long exposure times. The coloration process is reversible in the presence of oxygen gas.
Keywords: Tungsten oxide nanoparticles; Laser ablation; Gasochromic; Optical absorption;
Enhanced conductivity of novel star branched liquid crystalline copolymer based on poly(ethylene oxide) for solid polymer electrolytes by Yongfen Tong; Lie Chen; Yiwang Chen; Xiaohui He (10095-10103).
Display Omitted► Novel star branched amphiphilic liquid crystalline copolymers are prepared by atom-transfer radical polymerization. ► Lamellar structures are achieved by cooperative assembly of hydrophobic mesogen-containing polymethacrylate and the amorphous hydrophilic TPEO nanoscale aggregation. ► The ionic conductivity has been improved greatly by incorporation of the mesogens.Novel star branched amphiphilic liquid crystalline (LC) copolymers, namely, 4-Arm poly(ethylene oxide)-co-x-[(4-cyano-4′-biphenyl)oxy]alkyl methacrylate (TPEO-MAxLC-Φ) (x = 6, Φ = 20, 30; x = 9, Φ = 10, 19) containing cyanobiphenyl mesogenic pendants (MAxLC) are prepared by atom-transfer radical polymerization (ATRP). The effects of structural variations on the properties, and the relationship between morphology and the ionic conductivity of the copolymer electrolytes are studied. The strong assembly of cyanobiphenyl mesogens induces the copolymers with enantiotropic mesophase, even after doped with LiClO4. And lamellar structures are also achieved by cooperative assembly of hydrophobic mesogen-containing polymethacrylate groups and the hydrophilic TPEO nanoscale aggregation, especially after LC thermal annealing. The ionic conductivity has been improved greatly by incorporation of the cyanobiphenyl mesogens. This is because the mesogens not only favor the ordered morphology to provide the efficient ion transportation pathway, but also suppress TPEO crystallization to offer the movement of TPEO chains. Among all of the electrolyte films, TPEO-MA9LC-19 shows the best ion conductivity of 2.24 × 10−5 S cm−1 at 25 °C and even reaches to 5.39 × 10−5 S cm−1 after annealed at LC states.
Keywords: Polymer electrolytes; Star branch; Liquid crystals; Ionic conductivity;
Synthesis of Pd/ZnO nanocomposites with high photocatalytic performance by a solvothermal method by Yunyan Zhang; Qiuling Wang; Jian Xu; Shiyu Ma (10104-10109).
► Pd/ZnO nanocomposites can be obtained through a facile one-pot solvothermal method. ► No extra surfactant or template was added in the reaction process. ► Pd/ZnO shows good photocatalytic activity and high stability. ► Pd/ZnO shows strong PL in UV region and weak emission in visible region.In this study, Pd/ZnO nanocomposites were prepared through a facile one-pot solvothermal method without using any extra surfactant or template. During the reaction, hexamethylenetetramine (HMT) can release ammonia and formaldehyde, which are used as a precipitant for the fabrication of ZnO and a reducing agent for the formation of metal Pd, respectively. On the other hand, alcohol restricts the growth of ZnO and nanosized ZnO samples are obtained. The results of photocatalysis demonstrate that Pd/ZnO nanocomposites show good photocatalytic performance and high stability for degradation of organic pollution due to the effective separation of electron–hole pairs and the high specific surface of the samples. In addition, the 0.73 wt.% Pd/ZnO nanocomposites show strong UV emission and weak visible emission, which can be attributed to the formation of interface between Pd and ZnO.
Keywords: ZnO; Pd; Nanocomposites; Solvothermal; Photocatalysis; Photoluminescence;
Adhesion strength characterization of PVDF/HA coating on cp Ti surface modified by laser beam irradiation by A.A. Ribeiro; L.G. Vaz; A.C. Guastaldi; J.S.C. Campos (10110-10114).
► Titanium substrates are superficially treated by laser beam irradiation. ► Treated titanium substrates are coated with α-PVDF and α-PVDF/HA films. ► Three-point bending test is used to assess the adhesion strength of coatings. ► The coatings show good physical adhesion on treated titanium substrates. ► Three-point bending test appears as an alternative for measuring adhesion strength.Up to the moment, there is no standardized test for measuring the adhesion strength of polymeric coatings on titanium substrate modified by laser beam irradiation. The present work aimed to assess the adhesion strength of polyvinylidene fluoride (α-PVDF)/hydroxyapatite (HA) composite coating on commercially pure titanium (α-cp Ti) substrate surface modified by laser beam irradiation, using the three-point bending test. The preparation of coating was carried out by mixing α-PVDF pellets dissolved in dimethylacetamide (DMA) with HA/DMA emulsion. The mixture was poured onto the α-cp Ti sample and left to dry in an oven. Commercially pure titanium plates were coated with α-PVDF/HA composite film, in proportions of 100/00 (PVDF) and 60/40 (PVDF/HA) in weight. The Ti-PVDF/HA samples were subjected to the three-point bending test and analyzed by scanning electron microscopy. According to the results, PVDF and PVDF/HA coatings showed a good adhesion strength on α-cp Ti surface, since no detachment was observed.
Keywords: Polyvinylidene fluoride; Hydroxyapatite; Titanium; Laser beam irradiation; Coating; Adhesion strength; Biomaterial;
Functionalization of layered double hydroxides by intumescent flame retardant: Preparation, characterization, and application in ethylene vinyl acetate copolymer by Guobo Huang; Zhengdong Fei; Xiaoying Chen; Fangli Qiu; Xu Wang; Jianrong Gao (10115-10122).
► LDHs were modified with compound PAHPA. ► EVA/PAHPA-LDHs nanocomposites were prepared by melt blending. ► PAHPA-LDHs improved the flame retardancy of the nanocomposites.A phosphorus―nitrogen containing compound, N-(2-(5,5-dimethyl-1,3,2-dioxaphosphinyl-2-ylamino)-hexylacetamide-2-propyl acid (PAHPA), is synthesized and characterized. A novel flame retardant, namely layered double hydroxides (LDHs) modified with PAHPA (PAHPA-LDHs), is prepared by ion-exchange of LDHs with PAHPA. The results from Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and energy dispersive X-ray analysis with a high-angle annular dark-field scanning transmission electron microscope show that PAHPA intercalated LDHs. The X-ray diffraction and transmission electron microscopy (TEM) results show that PAHPA-LDHs achieve well dispersion in ethylene vinyl acetate copolymer (EVA) matrix and the EVA/PAHPA-LDHs nanocomposites (i.e. EVA filled with 5 wt% PAHPA-LDHs) are formed by polymer melt intercalation. Thermal stability and flammability properties are investigated by thermogravimetric analysis and cone calorimeter tests. The results show that the addition of PAHPA-LDHs improves thermal stability and reduces obviously the flammability of EVA resin. Compared with pure EVA resin, the peak heat release rate of the EVA/PAHPA-LDHs nanocomposites is reduced by about 43%. The results of scanning electron microscopy and TEM indicate that a compact and dense intumescent char is formed for the EVA/PAHPA-LDHs nanocomposites after combustion.
Keywords: Nanocomposites; Intumescent flame retardant; Layered double hydroxides;
Monitoring preparation and phase transitions of carburized W(1 1 0) by reflectance difference spectroscopy by Magdalena Bachmann; Norbert Memmel; Erminald Bertel; Mariella Denk; Michael Hohage; Peter Zeppenfeld (10123-10127).
► Real-time in situ monitoring of W(1 1 0) surface cleaning. ► Real-time in situ monitoring of carburazation kinetics on W(1 1 0) by RDS. ► Phase transformation R(15 × 3)-C/W(1 1 0)–R(15 × 12)-C/W(1 1 0) studied by RDS, AES and LEED.Reflectance difference spectroscopy (RDS) is applied to follow in situ the preparation of clean and carburized W(1 1 0) surfaces and to study the temperature-induced transition between the R(15 × 3) and R(15 × 12) carbon/tungsten surface phases. RDS data for this transition are compared to data obtained from Auger-electron spectroscopy and low-energy electron diffraction. All techniques reveal that this transition, occurring around 1870 K, is reversible with a small hysteresis, indicating a first-order-like behaviour. The present results also prove a high surface sensitivity of RDS, which is attributed to the excitation of electronic p-like surface resonances of W(1 1 0).
Keywords: Reflectance difference spectroscopy; Tungsten; Carbon; Phase transition; Auger-electron spectroscopy; Low-energy electron diffraction;
Improvement of oxidation resistance of copper by atomic layer deposition by M.L. Chang; T.C. Cheng; M.C. Lin; H.C. Lin; M.J. Chen (10128-10134).
Results of glancing incident angle diffraction (GIXD) show the bare-Cu specimen was attacked by oxidation, whereas the coated-Cu specimens prevented from this problem.Display Omitted► Deposition of Al2O3 films on pure copper by an atomic layer deposition (ALD) technique. ► Analysis of properties of the films coated at various substrate temperatures using the ALD technique. ► Identification of the improvement of oxidation resistance of pure copper by the ALD-Al2O3 films. ► Assessment of the durability of the ALD-Al2O3 films by adhesion strength.Al2O3 films were deposited by the atomic layer deposition (ALD) technique onto pure copper at temperatures in the range 100–200 °C. The chemical composition, microstructure, and mechanic properties of the ALD-deposited Al2O3 films were systematically analyzed. The variations in the film characteristics with substrate temperature were observed. Oxidation trials revealed that 20-nm-thick Al2O3 films deposited at a substrate temperature as low as 100 °C suppress oxidative attack on pure copper. The Al2O3 films also showed excellent durability of adhesion strength, according to predictions using the Coffin–Manson model based on the results of accelerated temperature cycling tests. These features indicate that ALD-deposited Al2O3 film is a very promising candidate to be a protective coating for pure copper.
Keywords: Atomic layer deposition; Al2O3 film; Copper; Oxidation resistance; Adhesion strength;
Magnetic and electronic properties of silicane with hydrogen vacancies on the surface by L. Pan; H.J. Liu; Y.W. Wen; X.J. Tan; H.Y. Lv; J. Shi; X.F. Tang (10135-10139).
► Controllable magnetism can be obtained by creating H vacancies on the silicane surface. ► The spins of unsaturated Si in the single-sided domain are ferromagnetically ordered. ► In contrast, the double-sided domain is anti-ferromagnetic. ► The creation of H vacancies induces additional flat bands in the original band structure. ► The band gap can be manipulated by changing the size and/or shape of a certain domain.By using first-principles pseudopotential calculations, we investigate the magnetic and electronic properties of hydrosilicon honeycomb structure (silicane) with hydrogen vacancies on its surface. It is found that a single vacancy created on the nonmagnetic silicane can induce a magnetic moment of one μ B . When a domain of vacancies is considered, the magnetization is determined by the size and geometry of the domain, and whether it is single- or double-sided. Compared with the energy band structure of silicane, the creation of domain causes very flat bands around the Fermi level and tends to reduce the band gap. It is interesting to find that the systems with single-sided domain all exhibit a band gap of about 1.0 eV while those of double-sided domain exhibit strong size dependence.
Keywords: Silicane; First-principles; Surface vacancies; Magnetic properties; Electronic properties;
Plasmon-assisted photoluminescence enhancement of SiC nanocrystals by proximal silver nanoparticles by N. Zhang; D.J. Dai; J.Y. Fan (10140-10143).
► We studied metal surface plasmon-enhanced photoluminescence in SiC nanocrystals. ► The integrated emission intensity can be enhanced by 17 times. ► The coupling between SiC emission and Ag plasmon oscillation induces the enhancement. ► The enhancement is tunable with varied spacing thickness of electrolytes.Plasmon-enhanced photoluminescence has wide application potential in many areas, whereas the underlying mechanism is still in debate. We report the photoluminescence enhancement in SiC nanocrystal–Ag nanoparticle coupled system spaced by the poly(styrene sulfonic acid) sodium salt/poly(allylamine hydrochloride) polyelectrolyte bilayers. The integrated luminescence intensity can be improved by up to 17 times. Our analysis indicates that the strong coupling between the SiC nanocrystals and the surface plasmon oscillation of the silver nanoparticles is the major cause of the luminescence enhancement. These findings will help to understand the photoluminescence enhancement mechanism as well as widen the applications of the SiC nanocrystals in photonics and life sciences.
Keywords: SiC nanocrystal; Enhanced photoluminescence; Surface plasmon;
Rapid preparation of highly ordered ultraflat ZnO surfaces by Jan Götzen; Gregor Witte (10144-10147).
► Fast preparation of atomically flat and unreconstructed ZnO single crystal surfaces (within less than 4 h). ► Exclusion of oxygen depletion by heating in air yields stoichiometrically correct surfaces. ► Applicable to various surface orientations. Validated for both polar basal planes of ZnO as well as for mixed terminated ZnO(1 0 −1 0) surface. ► Ultra-flat surfaces: atomically flat terraces of more than 0.5 μm separated only by monatomic steps.We report a simple procedure for preparing atomically flat and microscopically well ordered ZnO single crystal surfaces of various orientations which consists of an initial cleaning step by ion sputtering, followed by subsequent annealing in air. The resulting atomic ordering and morphology have been validated for both polar basal planes as well as the mixed terminated ( 1 0 1 ¯ 0 ) surface by means of low energy electron diffraction (LEED) and atomic force microscopy (AFM) and were further compared with other preparation schemes. It is demonstrated that this procedure allows a very rapid and reliable preparation of unreconstructed surfaces with extended terraces whose size is limited by the precision of the macroscopic sample orientation.
Keywords: ZnO; Single crystal surfaces; AFM; Surface morphology;
Mechanistic investigations on the adsorption of thiophene over Zn3NiO4 bimetallic oxide cluster by Shengli Zhang; Yonghong Zhang; Shiping Huang; Peng Wang; Huiping Tian (10148-10153).
Display Omitted► H2 plays an important role in the cleavage of C―S bonds of thiophene. ► The remaining S species on Ni site of Zn3NiO4 are dealt with two pathways. ► One is that nickel sulfide is reduced in the presence of H2 to form H2S. ► The other is that sulfur can be directly transferred from Ni site to Zn site. ► It favors the process that sulfur is directly transferred from Ni site to Zn site.Desulfurization mechanism of thiophene was studied via reactive adsorption over a Zn3NiO4 cluster by density functional theory calculations. A gas-phase thiophene molecule is adsorbed on the Ni site instead of Zn site in the Zn3NiO4 adsorbent. When the first H2 attacks C4H4S–adsorbent system, activation of the C―S bonds occurs. When the second H2 continues to attack the adsorption configuration, the C―S bonds are cracked. In the process, H2 plays an important role in the cleavage of the C―S bonds of organic sulfur compound. The remaining S species on the Ni site of Zn3NiO4 adsorbent are dealt with two pathways. One is that nickel sulfide is reduced in the presence of H2 to form H2S with an energy barrier of 0.859 eV, and then the active nickel species is liberated from nickel sulfide in the S–adsorbent system. The other is that sulfur can be directly transferred from Ni site to Zn site in the adsorbent with a smaller energy barrier of 0.634 eV. Thus, in a reaction adsorption desulfurization, it favors the process that sulfur is directly transferred from Ni site to Zn site.
Keywords: Reactive adsorption; Desulfurization mechanism; Thiophene; Zn3NiO4 cluster; Density functional theory;
Improvement of interfacial property between PBO fibers and epoxy resin by surface grafting of polyhedral oligomeric silsesquioxanes (POSS) by B. Song; L.H. Meng; Y.D. Huang (10154-10159).
► POSS nanoparticle was used as a novel coupled agent to enhance interface adhesion of PBO fibers with epoxy resin. The results show that octaglycidyldimethylsilyl POSS was grafted successfully on surface of PBO fibers. ► The surface morphology and surface chemical elemental composition of PBO fibers before and after modification were analyzed. ► The influence of POSS surface grafting on mechanical property and interfacial property of PBO fibers was investigated. Interfacial property was obviously enhanced, meanwhile mechanic property keep constant.PBO fiber as reinforced material has been widely applied in various fields such as aerospace, automobile and sport apparatus due to excellent mechanic property during past two decades. However, poor interfacial adhesion limits the further application of PBO fiber. To solve this problem, plenty of work has been done. In the present study, the surface of PBO fibers was treated through surface grafting of polyhedral oligomeric silsequioxanes (POSS). The effect of POSS grafting on bulk mechanic property and interfacial property of PBO fiber were studied. Surface chemical composition, surface morphologies, surface free energy, single-fiber tensile strength of untreated and treated PBO fiber were characterized. The results show that POSS nanoparticles were grafted on the fiber surface successfully. The surface characteristics of treated PBO fiber were different from that of untreated one. Oxygen-containing polar functional groups, elemental ratio of oxygen to carbon, surface roughness and surface free energy increased significantly. In addition, interfacial shear strength between treated PBO fibers and epoxy resin increased to 54.9 MPa comparative with untreated one. Meanwhile tensile strength of treated PBO fibers only very little decreased. Therefore, POSS surface grafting can be utilized to enhance the interfacial adhesion between PBO fibers and epoxy resin matrix.
Keywords: PBO fiber; Surface grafting; Polyhedral oligomeric silsequioxanes; Interfacial property; XPS; SEM;
Surface treatment of zinc coatings by molybdate solutions by L. Fachikov; D. Ivanova (10160-10167).
► Molybdate conversion treatments on zinc coatings. ► Zn, Mo, P, O and Ni are basic elements in the coatings. ► Better corrosion resistance of zinc coatings after molybdate surface treatment.The influence of different factors such as concentration, temperature, pH and cathodic polarization on formation, properties and composition of coatings obtained under treatment of zinc surfaces by molybdate solutions has been investigated by gravimetric, electrochemical and physical methods. Coatings obtained at pH 4 are distinguished for the best uniformity and density of color. The thicknesses of coatings raise by increasing the cathode current density under other equal conditions. Molybdenum, zinc and phosphorus are the basic components of the passive films.
Keywords: Zinc coatings; Non-chromate treatment; Molybdate treatment;
Surface treatment of para-aramid fiber by argon dielectric barrier discharge plasma at atmospheric pressure by Ruxi Gu; Junrong Yu; Chengcheng Hu; Lei Chen; Jing Zhu; Zuming Hu (10168-10174).
► We use DBD technique to modify the surface of Kelvar29 fibers. ► The changed parameters include treated power, time and argon flux. ► There exists an optimum experimental condition of plasma treatment. ► Adhesion and wettability properties of fibers are improved through plasma treatment.This paper is focused on influence of argon dielectric barrier discharge (DBD) plasma on the adhesive performance and wettability of para-aramid fibers and three parameters including treated power, exposure time and argon flux were detected. The interfacial shear strength (IFSS) was greatly increased by 28% with 300 W, 60 s, 2 L min−1 argon flux plasma treatment. The content of oxygen atom and oxygen-containing polar functional groups were enhanced after the argon plasma treated, so as the surface roughness, which contributed to the improvement of surface wettability and the decrease of contact angle with water. However, long-time exposure, exorbitant power or overlarge argon flux could partly destroy the prior effects of the treatment and damage the mechanical properties of fibers to some degree.
Keywords: Para-aramid fiber; Dielectric barrier discharge; Argon plasma; Adhesive performance; Wettability;
Synthesis and optical properties of three-dimensional nanowall ZnO film prepared by atmospheric pressure chemical vapor deposition by Zhenjun Li; Zuofu Hu; Li Jiang; Haiqin Huang; Fengjuan Liu; Xiqing Zhang; Yongsheng Wang; Penggang Yin; Lin Guo (10175-10179).
Display Omitted► Nanowall ZnO films were prepared by atmospheric pressure chemical vapor deposition. ► The high ordered nanowalls were assembled along three directions angled 120°. ► The ZnO films increased the probability of light internal refection and scattering. ► The nanowall films were suitable for fabricating solar cells and other devices.Without template, three-dimensional nanowall ZnO films were synthesized in an atmospheric pressure chemical vapor deposition (APCVD) system by adjusting zinc species concentration. In the high ordered film, the vertical nanosheets were assembled along three directions angled approximately 120°. The extremely strong ZnO (0 0 0 2) peaks in X-ray diffraction patterns testified the preferred (0 0 0 1) orientation and high crystalline quality of the films. The low transmittances of nanowall films were attributed to the strong inner reflection and scattering. These results show that the simplified APCVD method is potential in synthesizing uniform nanowall ZnO films.
Keywords: Zinc oxide; Nanowall film; Chemical vapor deposition; Optical property;
Size-controlled in situ synthesis and photo-responsive properties of silver/poly(methyl methacrylate) nanocomposite films with high silver content by Cheng Chen; Junguo Li; Guoqiang Luo; Yuanlu Xiong; Qiang Shen Lianmeng Zhang (10180-10184).
Display Omitted► Ag/PMMA nanocomposite films with high silver content are prepared by in situ synthesis. ► The size of Ag nanoparticles can be controlled by reaction time. ► The electrical properties of Ag/PMMA nanocomposites films shows enhancement compared with the pure PMMA. ► The recycle photo-responsive properties of Ag/PMMA nanocomposite films are proposed.Ag/PMMA nanocomposites have attracted much attention due to its superior mechanical, optical and electrical properties. In this article, Ag/PMMA nanocomposite films with high silver content (20 wt%) have been successfully in situ synthesized. UV–vis analysis, transmission electron microscopy (TEM), current–voltage (I–V) analysis, hall effect measurement system and electrochemical workstation are used to characterize the nanocomposite films. The results reveal that silver nanoparticles (NPs) homogeneously distribute in PMMA films and the particles size of silver NPs which has been controlled from 1.68 to 6.98 nm. Ag/PMMA nanocomposite films show electrical properties due to the conduction paths created by Ag nanoparticles. With the increasing diameter of silver NPs, the current density decreases and resistivity increases, respectively. Photo-responsive properties of Ag/PMMA nanocomposite films indicate that conduction paths could be destroyed by illumination and rebuilt in dark condition.
Keywords: In situ synthesis; Size-controlled; Thin films; Photo-responsive properties;
Oxygen-containing functionalities on the surface of multi-walled carbon nanotubes quantitatively determined by fluorescent labeling by Nikolay Dementev; Richard Ronca; Eric Borguet (10185-10190).
► Fluorescent labeling to quantify functional groups on multi-walled carbon nanotubes. ► Functional groups on as-received and on purified carbon nanotubes. ► Detection, identification and quantification of carbonyl, alcohol, and carboxyl surface functionalities. ► Purified material has a lower concentration of functional groups than the non-purified one. ► Effect of different content of carbon impurities in studied materials.Control over the type and concentration of functional groups on carbon nanotubes (CNTs) require the use of reliable and sensitive analytical methods to detect, identify and quantify the functionalities on the material. Here we report the results of the selective quantification of aldehyde (together with ketone), carboxylic, and alcohol groups on arc-produced multiwalled carbon nanotubes (MWCNTs) using fluorescent labeling of surface species (FLOSS), combined with surface area and thermogravimetric analysis. The high sensitivity of the fluorescence spectroscopy combined with the selectivity of the chemistry of covalent attachment, allowed us to determine that as-produced MWCNTs contain ∼1.1 at.% carboxylic groups, ∼2.0 at.% aldehydes (and ketones) and <2.0 at.% hydroxyls. Surprisingly, and contrary to the behavior of single walled carbon nanotubes, these concentrations do not appear to increase for acid purified MWCNTs but rather decrease to 0.4 at.% for carboxylic groups; 1.6 at.% for aldehydes (and ketones) and <3.0 at.%, for hydroxyls. Possible explanations for the observation that the acid purified MWCNTs have a lower level of the functionalities compared to the as-produced material are discussed.
Keywords: Carbon nanotubes; Fluorescence; Labeling; Functional groups; Surface characterization;
Crystallinity improvement of hexagonal boron nitride films by molybdenum catalysts during microwave plasma chemical vapor deposition and post-annealing by Fei Liu; Jie Yu; Xuedong Bai (10191-10194).
► Introduce catalyzing effects into the MPCVD process for high quality hBN films. ► This mild synthesizing method can be easily used for device application. ► hBN films prepared by Mo catalyst have a relatively good light emission property.Hexagonal boron nitride (hBN) is a promising deep ultraviolet light emitter. Here we report the catalytic growth of hBN films by microwave plasma chemical vapor deposition (MPCVD). The hBN films were first grown on Mo/Si substrate from a gas mixture of N2, BF3, and H2 and then annealed in nitrogen for 3 h at 900 °C. The Mo catalysts exhibit obvious catalyzing effects in improving the crystallinity of the hBN films during the growth and annealing processes. Well-crystallized hBN films with small Raman peak width of 9.3 cm−1 and sharp photoluminescence emission peak at 293 nm were obtained.
Keywords: Hexagonal boron nitride; Molybdenum catalysts; Chemical vapor deposition; Post-annealing; Photoluminescence;
Characterization of Cu(In,Ga)Se2 films deposited by single-step electron beam evaporation for solar cell applications by Chuanling Men; Ziao Tian; Qiuping Shao; Hua Zhang; Zhenghua An (10195-10198).
► CIGS thin films are formed on CIGS powder source by single-step electron-beam evaporation method. ► Stoichiometric CuIn0.7Ga0.3Se2 with chalcopyrite structure and preferential orientation (1 1 2) with good crystalline quality is obtained. ► The optimal deposition condition included a high substrate temperature of 650 °C and a high acceleration voltage of 10 kV.CuIn x Ga(1−x)Se2 (CIGS) thin films have been prepared by a single step of electron beam evaporation of a mixed alloy power made of high purity elemental copper, indium, gallium and selenium. The crystalline quality of CIGS films increases with increasing the substrate temperature, and stoichiometric CuIn0.7Ga0.3Se2 with chalcopyrite phase and (1 1 2) preferential orientation can be obtained at a substrate temperature of 650 °C. X-ray diffractometer (XRD), scanning electron microscope (SEM) and absorption spectroscopy are used to characterize the obtained films. CuIn0.7Ga0.3Se2 films evaporated at 650 °C is found to have a bandgap of about ∼1.11 eV. In addition, two different acceleration voltages (5 kV and 10 kV) for the electron gun are also compared and a high acceleration voltage is found to be crucial in order to obtain stoichiometric CIGS films without Cu-deficiency. Our results suggest that the single-step electron beam evaporation at a high acceleration voltage could be potentially applied for fabrication of CIGS thin solar cells.
Keywords: Cu(In,Ga)Se2; Electron-beam evaporation; XRD; SEM;
Superhydrophobic surfaces fabricated by surface modification of alumina particles by Edna Richard; S.T. Aruna; Bharathibai J. Basu (10199-10204).
► Fabrication of superhydrophobic alumina surfaces with different particle sizes. ► Superhydrophobicity due to the micronanostructure and low surface energy. ► Lowest surface area fraction of solid value facilitated superhydrophobicity. ► Potential application for creating superhydrophobic surface on cotton fabrics.The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of <2°. Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.
Keywords: Alumina; Particle size; Superhydrophobic; Water contact angle;
Water breakthrough pressure of cotton fabrics treated with fluorinated silsesquioxane/fluoroelastomer coatings by Kevin R. Lamison; Andrew J. Guenthner; Joseph M. Mabry (10205-10208).
► Cotton fabric with fluoro-POSS treatment shows water breakthrough pressure near 1 kPa. ► Agreement between model prediction based on filament geometry and experimental data. ► Effect of dip coating process variables on the experimentally observed breakthrough pressure.Breakthrough pressure is an important parameter associated with the performance of water-resistant fabrics. Hydrostatic testing has been utilized to experimentally determine the breakthrough pressure of commercial cotton fabrics treated with various combinations of octakis(1H,1H,2H,2H-perfluorodecyl) polyhedral oligomeric silsesquioxane (F-POSS), a compound with the lowest reported solid surface energy, and the commercial fluoroelastomer, Tecnoflon®. The breakthrough pressure values (amounting to a few inches of water) were found to be similar to predicted values based on the geometry of the samples and the surface energy of the components. The theoretical predictions, however, do not explain all differences observed among samples, such as the fact that a single dip coating with both F-POSS and Tecnoflon® produced a higher breakthrough pressure than a single dip coating in either F-POSS or Tecnoflon®, or sequential dip coating (in either order) of the two components. SEM analysis of the coated fabrics indicated that coatings were conformal at the microscale, but did result in sub-micron scale roughness. Although this roughness may help to increase the contact angles with water, the breakthrough pressure appeared to be primarily determined by the geometry of the individual filaments.
Keywords: Breakthrough pressure; F-POSS; Superhydrophobic; Dip-coating;