Inorganic Materials (v.46, #3)

IR spectroscopic study of hydrogenated silicon layers by S. P. Timoshenkov; O. M. Britkov; V. V. Kalugin; Yu. Ya. Lapitskii; V. P. Pelipas; B. M. Simonov (217-220).
Proton-implanted (100) KEF-4.5 (phosphorus-doped) silicon wafers 460 μm in thickness have been studied by IR spectroscopy in an on-axis geometry. The implantation process has been run at increased proton energies and current densities to rather high implant doses, up to 7.1 × 1017 H+/cm2. The results are used to identify the structure of chemical bonds in the hydrogen centers produced by the implantation and subsequent annealing at 550°C. We show that the assignment of absorption bands to particular Si-H x (x = 1–3) bonds must take into account the substrate temperature during the implantation process and the annealing temperature.

Atomic force microscopy and X-ray photoelectron spectroscopy study of chitosan-carbon fiber materials by Yu. M. Nikolenko; V. G. Kuryavyi; I. V. Sheveleva; L. A. Zemskova; V. I. Sergienko (221-225).
Chitosan-carbon materials produced by electrochemical deposition of chitosan on an activated carbon fiber (ACF) as an electrode have been studied by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM data demonstrate that the microstructure of the coating depends on whether chitosan is deposited in soluble or insoluble form. XPS data are used to evaluate the state of chitosan in the composites in relation to the deposition conditions.

The phase composition and magnetic state of Mn1 + x Sb (0 ≤ x ≤ 1.0) alloys have been determined before and after high-pressure high-temperature processing (p = 8 GPa, T = 2300 K). Exposure to high pressure and temperature is shown to extend the homogeneity range of hexagonal Mn1 + x Sb alloys (sp. gr. P63/mmc, no. 194) to x = 0.5. The alloys with x > 0.5 consist of two phases: hexagonal Mn1 + x Sb and cubic Mn3Sb (sp. gr. Pm3m, no. 221). The magnetic state of the alloys containing manganese in excess of the equiatomic composition can be understood in terms of a two sublattice model and ferrimagnetic ordering.

Effect of Au and NiO catalysts on the NO2 sensing properties of nanocrystalline SnO2 by S. M. Badalyan; M. N. Rumyantseva; S. A. Nikolaev; A. V. Marikutsa; V. V. Smirnov; A. S. Alikhanian; A. M. Gaskov (232-236).
Nanocrystalline tin dioxide has been synthesized, and its surface has been modified with Au and NiO. Their distributions in the nanocrystalline tin dioxide have been examined by X-ray diffraction and transmission electron microscopy. The NO2 sensing properties of the materials have been studied in the range 100–1000 ppb. Both gold and nickel enhance the NO2 response of SnO2. Codoping with Au and NiO markedly enhances its sensing response and, in addition, lowers the peak response temperature. The observed effect of NO2 concentration in dry air on the sensing response of the SnO2〈Au, NiO〉 nanocomposite can be understood in terms of the sequence of processes that take place on the SnO2 surface upon nitrogen dioxide adsorption in the presence of chemisorbed oxygen.

We have studied the effect of heat treatment of the starting BaTiO3 powder on the dielectric properties and microstructure of X7R-type BaTiO3-based ceramics. The results demonstrate that annealing of BaTiO3 stabilizes the degree of tetragonality in the crystal lattice of the ceramics. Microstructural analysis shows that the annealing temperature has no effect on the average grain size of the ceramics. Increasing the BaTiO3 annealing temperature increases the dielectric permittivity of the core phase and reduces the temperature coefficient of capacitance (TCC). We obtained an X7R-type BaTiO3-based ceramic material (BaTiO3 annealing temperature, 1150°C; firing temperature, 1160°C) with the following properties: ɛ25°C = 2230, TCC = ±12% (−55 to 125°C), and tanδ25°C = 0.013.

The phase equilibria in the “CaAl2Si3O10”-Na2Al2Si3O10-H2O system are analyzed using structural and thermal analysis data, and the ideal gonnardite structure is modeled. The results suggest that, to ensure a better correlation with the structures of the zeolites in this series, a new structural model of the gonnardite-based solid solution must be selected, with the structure rotated through 45° about the c axis in the ab plane.

Preparation of trichlorosilane from hydrogenation of silicon tetrachloride in thermal plasma by Qingyou Wu; Hanbin Chen; Yuliang Li; Xumei Tao; Zhijun Huang; Shuyong Shang; Yongxiang Yin; Xiaoyan Dai (251-254).
A new method of producing trichlorosilane by hydrogenation of silicon tetrachloride with assistance of DC charged thermo-plasma was proposed. We have studied the dependence of degree of disassociation and ionization of hydrogen on temperature, as well as the function of heat capacity, via which the optimal volume and H2: SiCl4 molar ratio were confirmed. A DC power of 50 kW was equipped and the highest yield of trichlorosilane was above 70%, with an average yield about 60% and minimum unit energy expenditure about 3.2 kWh/kg for SiHCl3. This process is possible to be industrialized.

Growth of structurally homogeneous CVD ZnSe plates by E. M. Gavrishchuk; V. B. Ikonnikov; L. A. Kuznetsov; S. M. Mazavin (255-258).
A model for the formation of the CVD ZnSe structure is proposed which takes into account the heat exchange between the surface of the growing crystal and the flow of gaseous reactants and the secondary recrystallization process at a varied substrate temperature. The calculation results are compared to experimental data. The time variation of the substrate temperature is optimized to achieve CVD of ZnSe with a homogeneous structure across the plate.

We examine the etching and chemomechanical polishing of zinc selenide with the use of aqueous solutions of inorganic acids and bases of different concentrations. The results are used to develop a procedure for chemomechanical polishing of polycrystalline zinc selenide.

Mechanical polishing of ZnSe using rosin-based resins by E. Yu. Vilkova; O. V. Timofeev (264-268).
We examine mechanical polishing of zinc selenide on rosin-based resins and the effect of the properties of the resins on the material removal rate and the surface quality of polished optical components from polycrystalline zinc selenide. The surface quality is shown to strongly depend on the composition and thermophysical characteristics of the polishing resin.

This paper examines the use of coulometric titration in studies of the nonstoichiometry, defect structure, and thermodynamic properties of semiconductor materials and also for doping of a number of chalcogenides with lead, copper, and germanium. A direct relationship is established between the thermodynamic and electrical properties of the binary compound semiconductors Pb1 ± δX (X = S, Se, Te), Cu2 ± δSe, and Cd2 ± δSe and the ternary spinel semiconductors Cd1 − δCr2Se4 and Cu1 ± δCr2S4 within their homogeneity ranges. The width and symmetry of the homogeneity range of these semiconductor materials are determined using coulometric titration in combination with emf and electrical conductivity measurements. Electrochemically doped nonstoichiometric copper selenide samples are shown to have compositions in the range Cu1.27Se–Cu2.73Se.

Thermal decomposition of arsine, a lewisite detoxification by-product by V. A. Fedorov; N. A. Potolokov; E. G. Zhukov; S. V. Nikolashin; A. V. Smetanin; S. A. Borisov; V. I. Kholstov (276-281).
We developed the physicochemical principles of the thermal decomposition of arsine resulting from the electrochemical reduction of the products of lewisite detoxification by alkaline hydrolysis. The thermodynamic and kinetic parameters of the thermal dissociation of arsine were calculated for the temperature range of practical interest in order to minimize the arsine concentration in the effluent gas. A process was proposed and tested for processing lewisite detoxification products which includes the thermal decomposition of arsine. The resultant arsenic is 99.9999% pure. Based on the scientific and technological foundations of arsine pyrolysis, we designed a system for the thermal decomposition of arsine, which was integrated into a lewisite detoxification process.

Obtaining of high-purity titanium, zirconium, and hafnium by the method of iodide refining in industrial conditions by M. L. Kotsar’; O. G. Morenko; M. G. Shtutsa; S. G. Akhtonov; A. V. Aleksandrov; A. G. Ziganshin; S. I. Indyk; E. N. Kucheryavenko; V. V. Lazarenko; A. O. Lapidus; V. A. Pogadaev; A. M. Popov (282-290).
The processes of obtaining high-purity titanium, zirconium, and hafnium by the method of thermal dissociation of iodides are discussed. The data on cleaning of the metals from impurities in glass and metal closed-type vessels are presented. The types of vessels used in industry and the conditions of raw stock pretreatment and iodide refining of titanium, zirconium, and hafnium are described.

Effect of the purity of starting materials on the structure and properties of permanent magnets by I. V. Belyaev; K. V. Grigorovich; N. B. Kolchugina; S. S. Shibaev (291-294).
The need for using pure starting components in the production of Alnico and Nd-Fe-B system alloys for permanent magnets of high quality is substantiated. The content of gas-forming impurities and nonmetallic inclusions was shown to affect substantially the formation of perfect structure of Alnico-type magnets; optimum conditions of preliminary treatment of the melt to decrease the content of gas-forming elements in ingots were determined. The negative effect of the contamination of starting materials with respect to gas-forming elements was determined and correlations between the oxygen content in Nd-Fe-B magnets and their properties were analyzed.

Effect of ligand environment on the physicochemical properties of aluminum alkoxide mixtures by V. V. Drobotenko; S. S. Balabanov; T. I. Storozheva (295-298).
This work examines the effect of ligand environment on the physicochemical properties of aluminum alkoxides containing different numbers of primary, secondary, and tertiary alkoxy groups. It is shown that aluminum alkoxides containing equal numbers of alkoxy groups differing in electronegativity are always crystalline. At other ratios, crystallization is kinetically hindered or impossible. Hydrolysis of aluminum alkoxides by atmospheric moisture leads to the formation of amorphous alcohol-containing products, which dissolve in water in the presence of nitric acid to form aluminum hydroxide sol. The hydrolysis products convert to α-Al2O3 starting at 1190°C, without γ-Al2O3 formation, as distinct from the products obtained via alkoxide hydrolysis by water in liquid phase.

Effects of Yb3+ and Er3+ concentrations and doping procedure on excitation transfer efficiency in Er-Yb doped phosphosilicate fibers by M. A. Melkumov; A. Yu. Laptev; M. V. Yashkov; N. N. Vechkanov; A. N. Guryanov; I. A. Bufetov (299-303).
We have studied the effects of preform fabrication procedure and ytterbium and erbium concentrations on the efficiency of excitation transfer from Yb3+ to Er3+ and lasing on erbium transitions in the range 1.53–1.61 μm in phosphosilicate glass fibers. The results indicate that the fabrication of fiber preforms by different MCVD-based processes has no effect on the excitation transfer efficiency. In the ranges 0.07–0.4wt % Er3+ and ∼ 0.4–8 wt % Yb3+ (Yb/Er ratio from ∼ 5 to 40), the excitation transfer efficiency is determined by the ytterbium concentration and is essentially independent of erbium concentration.

Molten glass flow stability during fiber drawing through a nozzle by M. F. Churbanov; G. E. Snopatin; V. V. Shabarov (304-309).
We report a computer simulation study of the diameter uniformity of optical fibers produced by drawing through a nozzle. We determine the natural frequency and decrement of melt flow rate oscillations downstream of the nozzle and examine the effect of temperature ripple on deviations of the fiber diameter from its nominal value. It is shown that cooling the melt jet stabilizes the melt flow and the fiber diameter.

Approaches to improving the accuracy in X-ray fluorescence analysis of Si1 − x Ge x films by N. I. Mashin; A. A. Leont’eva; R. V. Lebedeva; A. N. Tumanova (310-313).
This work examines approaches to improving the accuracy in the X-ray fluorescence determination of the composition and thickness of thin Si1 − x Ge x films on Polikor alumina substrates. We calculate correction coefficients that take into account the interelement effects in the films and demonstrate the possibility of reaching the required accuracy level in determining film composition and thickness. The results are used to optimize conditions for the preparation of films with tailored electrical properties.

Removal of barium impurities from selenium by vacuum distillation by V. S. Shiryaev; V. G. Pimenov; M. M. Lipatova; I. I. Evdokimov; M. F. Churbanov; Yu. P. Kirillov; V. N. Kornoukhov (314-317).
We have studied the behavior of barium impurities in the form of BaF2 and BaO during vacuum distillation of selenium. The effective Ba partition coefficient is shown to depend on the impurity concentration and evaporation rate. At initial barium contents in the range 3 × 10−3 to 2 × 10−5 wt %, the effective Ba partition coefficient is 600 and 1.5 at distillation rates of 4.7 × 10−6 and 1.5 × 10−3 cm3/(cm2 s), respectively. The chemical form of barium has no significant effect on its partition coefficient. Using a Rayleigh distillation equation, we have determined the equilibrium partition coefficient and the thickness of the diffusion boundary layer in the system.

A procedure has been developed for the determination of impurities in aluminum isopropoxide by inductively coupled plasma atomic emission spectrometry. The matrix effect has been compensated by adding a Bi internal standard. The detection limits of impurities are 10−7 to 10−5 wt %.

Matrix effect in atomic emission determination of impurities in Cr2O3 by R. V. Lebedeva; A. A. Leont’eva; A. N. Tumanova; N. I. Mashin (323-325).
We have studied the influence of chromium content on calibration curves for atomic emission analysis of chromium oxide using graphite powder. The results demonstrate that the intensity of impurity lines in the system varies nonlinearly. The effect is interpreted in terms of possible underlying processes.

We describe a procedure for arc source chemical atomic emission analysis of high-purity TeO2-WO3 tellurite glasses using preconcentration of nonvolatile impurities via reactive vaporization of the major glass constituents by fluorination with xenon difluoride in an autoclave. The detection limits of impurities are 10−8 to 10−6 wt %.