Inorganic Materials (v.48, #4)
Interaction between multiply charged manganese nanoclusters and sulfur atoms in silicon by Z. M. Saparniyazova; M. K. Bakhadyrkhanov; O. E. Sattarov; Kh. M. Iliev; K. A. Ismailov; N. Norkulov; D. Zh. Asanov (325-328).
We have studied the interaction of manganese nanoclusters with sulfur atoms in silicon. The results indicate that both simultaneous and sequential codoping with manganese and sulfur has little effect on the electrical properties (resistivity, carrier mobility, and conductivity type) of silicon. There is no extrinsic photoconductivity in the IR spectral region, and the material has only a small positive magnetoresistance. According to electron paramagnetic resonance data, the material contains only atomic manganese. Sulfur atoms in the silicon lattice are assumed to facilitate the capture of doubly charged manganese interstitials (Mn2+) at negatively charged vacancies, resulting in the formation of a multicomponent impurity cluster of composition Si2S2+Mn2− in the silicon lattice throughout the crystal. The optimal thermal annealing conditions for the formation of such clusters are determined. The ability to produce Si2S2+Mn2− clusters with controlled concentration allows one to tailor the main fundamental parameters of silicon and opens up new possibilities for such materials in nano- and microelectronic device development.
Synthesis and properties of TlIn1 − x Gd x Se2 solid solutions by Ya. Yu. Guseinov; D. D. Bairamov; U. M. Mustafaeva; A. B. Magerramov (329-331).
This paper describes the synthesis and crystal growth of TlIn1 − x Gd x Se2 solid solutions and presents the T-x phase diagram of the TlInSe2-TlGdSe2 system. Partial gadolinium substitution for indium in TlInSe2 increases the microhardness and unit-cell parameters of the material and reduces its band gap. According to X-ray diffraction data for TlInSe2-TlGdSe2 crystals, the TlIn1 − x Gd x Se2 (0 < x ≤ 0.1) solid solutions crystallize in tetragonal symmetry and are isostructural with TlInSe2.
Thermodynamic properties of silver nanoclusters by A. N. Sirenko; D. K. Belashchenko (332-336).
Icosahedral models of magic number silver clusters have been constructed using molecular dynamics simulations with the Doyama-Kogure potential. We have calculated the energy, heat capacity, entropy, Gibbs energy change, and excess surface energy as functions of cluster size and temperature. The vibrational contributions to the heat capacity and entropy are weak functions of cluster size (N), and the statistical degeneracy is lifted starting at 250–300 K. The surface energy density of the silver clusters is size-independent down to N = 13. The saturated vapor pressure over the clusters has been estimated. The calculated thermodynamic properties of fcc silver agree well with standard thermodynamic data.
Fabrication of sections of a Nb3Sn-based rigid superconducting cable by V. N. Kolosov; A. A. Shevyrev (337-341).
Using Nb3Sn layers deposited onto the outer and inner surfaces of copper tubes 30 and 50 mm in diameter, we have fabricated sections of a rigid superconducting coaxial cable up to 1 m in length. The highest current-carrying capacity of the cable at 4.2 K was 800–850 A/mm, which corresponded to a critical current density of (5.0–5.5) × 1010 A/m2 in the Nb3Sn layer.
Phase composition of Al2O3 nanopowders prepared by plasma synthesis and heat-treated by V. P. Sirotinkin; V. F. Shamrai; A. V. Samokhin; N. V. Alekseev; M. A. Sinaiskii (342-349).
We present X-ray diffraction data for Al2O3 nanopowders prepared by oxidizing aluminum powder in an air plasma, followed by size separation via centrifugation and heat treatment.
Reaction between ∼0.7- to 1-μm α-Al2O3 particles and SiO2 during high-temperature sintering by A. N. Guryanov; M. V. Yashkov; A. N. Abramov; E. D. Shatailo; M. A. Melkumov; M. F. Torsunov; M. N. Kachenyuk (350-354).
Al2O3:Cr3+ and Al2O3:Ti3+ particles with an average size of ∼1 and 0.7 μm, respectively, have been prepared through mechanical grinding of bulk crystals. Using purpose-designed accessories made from chromium and titanium, we were able to prevent Fe contamination. We studied the reaction between α-Al2O3 and SiO2 particles during high-temperature sintering. The results demonstrate that, in this system at temperatures above 1300°C, corundum particles dissolve in silica to form mullite. The reaction temperature and rate depend on the particle size composition of the Al2O3. The heating rate is shown to influence the dissolution rate of corundum particles. Increasing the heating rate from 7 to 15°C/min shifts the dissolution range of alumina particles from 1500 to 1630°C.
Synthesis and properties of amorphous SiO2 nanoparticles by V. S. Rimkevich; A. A. Pushkin; I. V. Girenko (355-360).
We have studied the synthesis of amorphous silica nanoparticles through fluorination processing of quartz sand. The results demonstrate that synthesis conditions influence the physicochemical properties of the resultant amorphous silica. We have obtained silica-containing powders 17 to 89 nm in average particle size and 92 to 508 m2/g in specific surface area.
Dispersion characteristics of water- and gold-infiltrated opal photonic crystals by V. S. Gorelik; V. V. Filatov (361-367).
This paper presents a theoretical analysis of conditions for the propagation of electromagnetic waves in a wide frequency range (from the infrared to ultraviolet spectral region) in synthetic opals infiltrated with water and gold nanoparticles. A dispersion equation is derived which describes the dispersion law of both “right-hand” (right-hand system of the $$vec E$$ , $$vec H$$ , and $$vec k$$ vectors) and “left-hand” (left-hand system of the $$vec E$$ , $$vec H$$ , and $$vec k$$ vectors) electromagnetic waves in the crystals. We have determined the dispersion characteristics of the refractive index and broadband reflectance of the opals, group velocity dispersion, and effective mass dispersion for phonons and polaritons. Theoretical results are compared to measured reflection spectra.
Effect of surface modification with carbon-containing groups on the size, properties, and morphology of silica particles by E. Yu. Safronova; A. B. Il’in; A. A. Lysova; A. B. Yaroslavtsev (368-373).
We report the properties of hydrated silica surface-modified with aminopropyl, 3-(2-imidazolin-1-yl)propyl, or 1H,1H,2H,2H-perfluorodecyl. The modifier groups reside on the surface of the silica nanoparticles, as shown by NMR spectroscopy. We examine the effect of the nature and concentration of the modifier on the particle size and specific surface area of silica. Thermal analysis results demonstrate that the modified materials are stable up to 430°C.
Synthesis, structure, and properties of large surface area Fe3O4/SiO2 nanocomposites by L. S. Semko; S. V. Khutornoi; N. V. Abramov; P. P. Gorbik (374-381).
This paper describes procedures for the template synthesis of magnetically controlled, large surface area Fe3O4/SiO2 nanocomposites using sodium oleate as a template. The structure and magnetic properties of the nanocomposites have been investigated in relation to SiO2 content and the way in which sodium oleate had been added to the solution. The largest specific surface area (up to 400 m2/g) was reached when the nanocomposites were fabricated using magnetic fluids. The synthesized materials were tested as adsorbents.
Ionic conductivity of Li8 − 2x Sr x ZrO6 by M. I. Pantyukhina; M. S. Shchelkanova; S. V. Plaksin (382-385).
Li8 − 2x Sr x ZrO6 solid solutions have been synthesized, and their transport properties (electronic conductivity, temperature and composition dependences of their conductivity, and activation energy for conduction) have been studied using impedance spectroscopy. The results demonstrate that partial strontium substitution for lithium increases the conductivity of the materials relative to undoped Li8ZrO6.
Effect of sintering temperature on the density, piezodielectric response, and mechanical and elastic properties of materials of different functional groups by M. V. Talanov; I. A. Verbenko; L. A. Shilkina; L. A. Reznichenko (386-390).
This paper describes the synthesis of Ba-doped PbZn1/3Nb2/3O3-PbMg1/3Nb2/3O3-PbNi1/3Nb2/3O3-PbTiO3 multicomponent solid solutions rich in PbNi1/3Nb2/3O3, which include ferroelectric relaxors, ferroelectrics with a diffuse phase transition, and classic ferroelectrics, and presents the phase diagrams along three cuts through a section near PbNi1/3Nb2/3O3. We examine the effect of sintering temperature on the density, piezodielectric response, and mechanical and elastic properties of ceramics of different functional groups; optimize the conditions for the fabrication of such ceramics, and compare the performance parameters of the materials obtained with those of their commercially available analogs.
Growth of potassium titanyl phosphate crystals using polyphosphate solvents with WO3 additions by N. S. Martirosyan; A. E. Kokh; N. G. Kononova; K. A. Kokh (391-396).
The content of WO3 additions to polyphosphate fluxes has been optimized, and crystals have been grown from KTiOPO4-K6P4O13/WO3 and KTiOPO4-K4P2O7/WO3 high-temperature solutions. The crystals have been analyzed for W, and the tungsten distribution coefficients have been determined.
Catalytic activity of NASICON-type phosphates for ethanol dehydration and dehydrogenation by A. B. Il’in; S. A. Novikova; M. V. Sukhanov; M. M. Ermilova; N. V. Orekhova; A. B. Yaroslavtsev (397-401).
A1 ± x Zr2 − x M x (PO4)3 (A = H3O+, Li+; M = In, Nb; x = 0, 0.1, 0.2) NASICON-type materials have been prepared and characterized by X-ray diffraction, specific surface measurements (capillary condensation of nitrogen), and impedance spectroscopy. We have assessed their catalytic performance for ethanol dehydration and dehydrogenation. The results demonstrate that, when prepared with a large specific surface area, these materials are active catalysts for ethanol conversion to hydrocarbons.
Crystallization from Na2O-P2O5-Fe2O3-MIIO (MII = Mg, Ni) melts and the structure of Na4MgFe(PO4)3 by N. Yu. Strutynska; I. V. Zatovsky; M. M. Yatskin; N. S. Slobodyanik; I. V. Ogorodnyk (402-406).
We have studied general trends of phosphate crystallization from Na2O-P2O5-Fe2O3-MIIO (MII = Mg, Ni) high-temperature solutions at Na/P = 1.0−1.4, MII/Fe = 1.0, and Fe/P = 0.15 or 0.3, and identified the stability regions of the phosphates Na4MIIFe(PO4)3 (MII = Mg, Ni), NaFeP2O7, and Na2NiP2O7. The synthesized compounds have been characterized by X-ray powder diffraction and infrared spectroscopy. The structure of Na4MgFe(PO4)3 (sp. gr. $$Rar 3c$$ , a = 8.83954(13) Å, c = 21.4683(4) Å) has been determined by Rietveld powder diffraction analysis.
Preparation of weakly agglomerated yttrium aluminum garnet powders by burning a mixture of yttrium aluminum hydroxynitrates, urea, and acetic acid by S. S. Balabanov; E. M. Gavrishchuk; V. V. Drobotenko; E. E. Katkova; V. A. Krylov; T. I. Storozheva; O. Yu. Chernova (407-409).
We have optimized the composition of a mixture of aluminum yttrium hydroxynitrates, urea, and acetic acid for the self-propagating high-temperature synthesis of yttrium aluminum garnet (YAG) powder. The powder prepared in this way offers a low degree of agglomeration, and the ceramic produced from it has a low carbon content. A technique has been proposed for carbon determination in YAG ceramics through gas chromatographic analysis of the gaseous products of carbide hydrolysis after the dissolution of the ceramic in pyrophosphoric acid.
PZT-36/NiCo0.02Cu0.02Mn0.1Fe1.8O4 − δ magnetoelectric rod composites with 1-3, 3-1, and 1-1 connectivity by I. V. Lisnevskaya; T. G. Lupeiko (410-415).
We have developed a technique for the fabrication of piezoelectric/ferrite rod composites with 1-3, 3-1, and 1-1 connectivity, which has the advantage of employing piezoelectric ceramics poled under optimal conditions. All types of rod composites produced by this technique have better piezoelectric and magnetoelectric properties in comparison with 2-2 layered structures produced in the same way. The magnetoelectric coefficient of the composites has a maximum at equal volume fractions of the components (0.5PZT-36/0.5NiCo0.02Cu0.02Mn0.1Fe1.8O4 − δ), independent of the connectivity type of the composites. The best piezo- and magnetoelectric properties are offered by the 1-1 composites, which have ΔE/ΔH = 140 mV/(cm Oe) at 1 kHz. The ΔE/ΔH of the composites correlates with their |d 33/d 31| ratio: with a decrease in this ratio, the magnetoelectric coefficient increases.
X-ray diffraction study of the NaF-LiF-LaF3 eutectic in the liquid and solid states by V. E. Sokol’skii; A. S. Roik; V. P. Kazimirov; N. V. Faidyuk; R. N. Savchuk (416-422).
The NaF-LiF-LaF3 eutectic has been studied by X-ray diffraction in the liquid and solid states. The results demonstrate that, below the melting point of the eutectic, the composition studied is based on crystalline NaLaF4, LiF, and NaF. A key role in determining the melt structure is played by an ordered arrangement of the lanthanum cations. The fluorine atoms around the lanthanum cations form a distorted Bernal trigonal prism.
Carrier trapping and delocalization in PbI2-containing CdI2 crystals by A. V. Gal’chinskii; N. V. Gloskovskaya; L. I. Yaritskaya (423-427).
Two pairs of electron and hole traps have been identified in PbI2-containing CdI2 crystals in the range 80–305 K using a combination of thermally stimulated and photoinduced depolarization of a photoelectret state. The electron traps are identified as Pb+ centers in nanocrystalline 2H- and 4H-PbI2 inclusions in the CdI2 lattice. One of the hole centers is assumed to be a Pb2+ vacancy. All of the traps in the binary crystalline system are related to the presence of PbI2 impurities as a consequence of the formation of heterojunctions between the CdI2 matrix and nanocrystalline PbI2 inclusions. We have calculated the energy distribution for filled traps.
Chemical and physical transformations in Ge-S-I glass preparation by A. M. Kut’in; A. D. Plekhovich; A. P. Vel’muzhov; M. F. Churbanov (428-432).
Vapor pressure measurement results for a mixture of germanium tetraiodide and sulfur in the temperature range 150–300°C have been analyzed in terms of conditionally equilibrium states, and the degree of GeI4 conversion and temperature-dependent compositions of the condensed and vapor phases have been determined. We have obtained a consistent thermodynamic data set necessary for optimizing the preparation of Ge-S-I glasses from germanium tetraiodide and sulfur.
Mechanical properties of Nb2O5 and Ta2O5 prepared by different procedures by O. B. Shcherbina; M. N. Palatnikov; V. V. Efremov (433-438).
We have studied the mechanical properties of niobium pentoxide and tantalum pentoxide ceramics prepared by a conventional ceramic processing technique and by exposure to high-intensity light (HIL). The results demonstrate that, after HIL exposure in an optical furnace, the niobium pentoxide and tantalum pentoxide ceramics possess enhanced microhardness and improved mechanical properties (strength, fracture toughness, and brittle microstrength) owing to the formation of fractal micro- and nanostructures. With increasing exposure intensity, the strength of the Nb2O5 and Ta2O5 ceramics increases.