Inorganic Materials (v.49, #1)

Kinetics of catalytic hydrogen reduction of SiCl4 in the presence of nickel chloride by A. V. Vorotyntsev; G. M. Mochalov; V. M. Vorotyntsev (1-5).
We have studied the reduction of silicon tetrachloride in the presence of a nickel-chloride-based catalyst. The kinetics of the process have been analyzed and the order and activation energy of the reaction have been determined. One of the main reactions on the catalyst surface is the transfer of a chlorine atom from a chlorosilane molecule to a hydrogen molecule, resulting in the formation of hydrogen chloride. The proposed reaction mechanism is supported by X-ray diffraction and chemical analysis data.

Concept of impurity-dislocation magnetism in III–V compound semiconductors by V. P. Sanygin; E. A. Tishchenko; Dau Hieu Shi; A. D. Izotov (6-13).
The ability of dislocations to attract impurity atoms is examined from the viewpoint of the feasibility to produce linear, extended magnetic structures in transition-metal-doped diamagnetic III–V compound semiconductor hosts. To understand the possible formation mechanisms and expected properties of such structures, we analyze a number of experimental studies that address the precipitation of magnetically inactive atoms onto edge dislocations in metals and semiconductors. The general trends identified are used in analysis of the properties of magnetically active atoms located around dislocations. We examine the feasibility of creating novel magnetic semiconductors in which transition-metal-doped dislocations would serve as magnetic memory cells. The research direction addressed in this paper is defined as the concept of impurity-dislocation magnetism in III–V compound semiconductors.

We have examined the influence of external magnetic fields up to H = 14 T on the phase transitions of MnAs, MnAs0.99P0.01, and MnAs0.98P0.02 single crystals. The results indicate that there is structural instability of the crystal lattice, associated with anomalous compression at temperatures from $$T_{f_1 }$$ ≃ 250 K to the phase transition temperature T u and anomalous lattice expansion in the basal plane between T u and $$T_{f_2 }$$ ≃ 350 K. Near the first-order phase transition, the magnetic entropy change at a magnetic field change from 0 to 14 T is about 40 J/(kg K) in single-crystal MnAs and approaches 50 J/(kg K) in single-crystal MnAs0.98P0.02.

Cathodoluminescence of photosensitive CdSe layers grown in a quasi-closed system by E. A. Senokosov; V. I. Chukita; I. N. Odin; M. V. Chukichev; E. S. Abramova (18-21).
We report conditions for the growth of photosensitive CdSe epilayers on mica (muscovite) substrates in a quasi-closed system. At a substrate temperature of 600°C and source evaporation temperature of 680°C, the most perfect photosensitive wurtzite CdSe epilayers can be grown. Such layers show bright free-exciton luminescence at 78 K.

Electrical and optical properties of Al3+-intercalated InSe and GaSe by V. B. Boledzyuk; Z. D. Kovalyuk; M. N. Pyrlya; S. G. Barbutsa (22-27).
We have studied the electrochemical, electrical, and optical properties of aluminum-intercalated indium and gallium monoselenides. Electron probe X-ray microanalysis data demonstrate that aluminum ions are incorporated into the host together with their solvation shell. Such Al3+ incorporation leads to changes in the electrical properties of InSe layered crystals when the intercalate concentration reaches the level N Al ∼ 1020 to 1021 cm−3, which corresponds to the formation of the final reaction product [Al x + (R-PC)y]InSe (where PC stands for propylene carbonate). At 77 K, the energy position of the exciton peak in the Al x InSe and Al x GaSe intercalation compounds is a nonmonotonic function of aluminum concentration.

Preparation and properties of the (TlInSe2)0.96Se0.04 solid solution by A. I. Nadjafov; O. Z. Alekperov; G. G. Guseinov; A. P. Abdullaev (28-32).
TlInSe2-rich TlInSe2-Se alloys (0–10 mol % Se) have been studied by X-ray diffraction. In the composition range 2.0–6.0 mol % Se, the TlInSe2-based α-solid solutions decompose by a peritectoid reaction at 363 K. The space group of the (TlInSe2)0.96Se0.04 solid solution is P222, and its lattice parameters are a = 6.575 ± 0.001 Å, b = 10.080 ± 0.001 Å, and c = 11.280 ± 0.001 Å. The electrical conductivity of singlecrystal samples of this solid solution is (0.5–3.0) × 10−3 S/cm at room temperature and varies little at temperatures from 85 to 280 K.

Transport properties of Cu5SmSe4 by R. N. Ragimov; E. R. Alieva; A. A. Khalilova; E. A. Jafarova (33-38).
The electrical conductivity, Hall coefficient, thermoelectric power, and thermal conductivity of Cu5SmSe4 have been measured at temperatures from 80 to 400 K, and its linear thermal expansion coefficient has been determined from X-ray diffraction data. The observed negative a-axis linear thermal expansion coefficient and anomalies in temperature-dependent transport properties of this compound are tentatively attributed to a transition of the samarium atoms from a divalent to a trivalent state.

Quantum-size PbSe-based island films by O. I. Rabinovich; A. R. Kushkhov; D. S. Gaev (39-42).
Controlled displacement of phase equilibria through the incongruent evaporation of Pb1 − x Se x films has been used to grow PbSe nanoisland films. The effect of growth conditions on the island size distribution has been studied.

Formation of an ordered structure in the Cu-49 at % Pd alloy by A. Yu. Volkov; O. S. Novikova; B. D. Antonov (43-48).
We compare the kinetics of the formation of an ordered structure in the Cu-49 at % Pd alloy in various initial states and demonstrate that the alloy can be brought into a single-phase, B2-ordered state, at variance with the commonly accepted Cu-Pd phase diagram. The alloy in this structural state has an extremely low resistivity: ρ = 5.48 × 10−8 Ω m.

Pyrolytic densification of porous carbon-carbon composite materials by A. Yu. Tolbin; B. V. Spitsyn; A. A. Serdan; A. A. Averin; A. P. Malakho; A. V. Kepman; N. E. Sorokina; V. V. Avdeev (49-56).
This paper examines the densification of the pore space of a carbon-carbon composite material through methane pyrolysis at a reduced pressure and the dynamics of the pyrolytic saturation process. The morphology and microstructure of the pyrolytic carbon are compared to those of the main components of the parent carbon-carbon composite material. The composite is characterized by hardness tests before and after the pyrolytic densification of the carbon matrix.

Composition, structure, and dielectric properties of SiC-AlN ceramic materials by G. K. Safaraliev; Sh. Sh. Shabanov; S. A. Sadykov; B. A. Bilalov; A. Sh. Agalarov (57-61).
We have studied the structure, relative dielectric permittivity (ɛ), and dielectric loss tangent (tanδ) of SiC-AlN ceramic materials. The results demonstrate that both ɛ and tanδ are anomalously high in the composition range 30–50 wt % AlN at low frequencies (0.1 kHz). We show that the increase in ɛ may be due to a barrier effect on silicon carbide and aluminum nitride grain boundaries and to migration polarization.

Preparation of nanostructured TiC x O y by D. A. Davydov (62-65).
Nonstoichiometric titanium oxycarbide, TiC x O y , nanopowder consisting of isolated stable nanoparticles with an average size of 40 ± 10 nm has been prepared by two-step synthesis from metallic titanium and oxalic acid. The nanostructured precipitate obtained by reacting titanium and oxalic acid was reduced by carbon in the process of solid-state sintering in vacuum. We examine the capabilities of this approach, which allows one to control the average particle size and composition of titanium oxycarbide.

Preparation of extrapure zinc oxide and zinc acetate from diethylzinc by I. A. Feshchenko; Yu. N. Tsinovoi; A. V. Tainov (66-69).
We have developed a process for the preparation of extrapure zinc oxide and zinc acetate from diethylzinc, which includes ultrapurification of this compound through low-pressure fractional distillation, oxygen oxidation of the purified diethylzinc in combustion mode, and heat treatment of the resultant zinc oxide. Zinc acetate was obtained by dissolving the zinc oxide in acetic acid. The content of regulated metallic impurities (iron, copper, aluminum, silicon, cadmium, nickel, cobalt, tin, lead, chromium, molybdenum, and magnesium) in the zinc oxide and zinc acetate was 10−5 to 10−6 wt %, and their net content was <5 × 10−4 wt %.

Structural and electrical properties of nanostructured fluorite-like R2 + x TiO5 + 1.5x (R = Y, Er; 0 ≤ x ≤ 1) by L. P. Lyashenko; L. G. Shcherbakova; D. A. Belov; E. I. Knerel’man; N. N. Dremova (70-75).
We have studied the detailed structure and electrical properties of single-crystal and polycrystalline fluorite-like R2 + x TiO5 + 1.5x (R = Y, Er; 0 ≤ x ≤ 1) materials and found the first evidence for the formation of nanodomains ≏ 40–1000 nm in size, which are coherent with the matrix and have various degrees of structural order. The formation of the nanodomains is driven by internal stress. Using impedance spectroscopy, we have determined the electrical conductivity of the materials in air at temperatures from 300 to 1000°C. The 1000°C electrical conductivity of Y2TiO5 (Er2TiO5) and Y2.44TiO5.67 (Er2.44TiO5.67) is 1.86 × 10−3 (1.35 × 10−3) and 9.98 × 10−4 (8.13 × 10−4) S/cm, respectively. The effective activation energy for electrical conduction in Y2TiO5 (Er2TiO5) and Y2.44TiO5.67 (Er2.44TiO5.67) is 1.16 (1.21) and 1.25 (1.21) eV, respectively.

Synthesis and luminescence of ultrafine Er3+- and Yb3+-doped Gd11SiP3O26 and Gd14B6Ge2O34 particles for cancer diagnostics by V. A. Krut’ko; A. V. Ryabova; M. G. Komova; A. V. Popov; V. V. Volkov; Yu. F. Kargin; V. B. Loshchenov (76-81).
In search of new contrast materials for NMR and fluorescence diagnostics and neutron capture therapy of cancer, we have synthesized ultrafine Er3+- and Yb3+-doped Gd11SiP3O26 and Gd14B6Ge2O34 particles and studied their luminescence properties. We measured the Er3+ upconversion luminescence spectra of the gadolinium erbium ytterbium phosphosilicates and borate germanates in the visible range and evaluated the absolute quantum yield of their luminescence. The quantum yield of luminescence in the gadolinium phosphosilicate Gd11SiP3O26 doped with 5.0 at % Yb and 2.5 at % Er is comparable to that in known Yb3+/Er3+ codoped fluorides. The nonradiative Yb3+ → Er3+ energy transfer efficiency is evaluated.

Phosphors based on NaZr2(PO4)3-type calcium and strontium phosphates activated with Eu2+ and Sm3+ by B. Glorieux; V. Jubera; A. I. Orlova; A. E. Kanunov; A. Garcia; C. Pallier; T. A. Oleneva (82-88).
Ca0.5Zr2(PO4)3:Eu2+, Sr0.5Zr2(PO4)3:Eu2+, and Ca0.5Zr2(PO4)3:Eu2+, Sm3+ orthophosphates prepared through precipitation using sol-gel processes are analogs of NaZr2(PO4)3 (NZP) and crystallize in space group R $$ar 3$$ . Their crystallographic parameters determined by X-ray diffraction are consistent with the interatomic distances extracted from EXAFS data. Their luminescence spectra obtained under excitation in the range 300–400 nm contain emission bands between 425 and 525 nm. Substitution of the larger sized cations Eu2+ and Sm3+ for Ca2+ shifts the emission bands to shorter wavelengths and reduces their width because of the decrease in the effect of the crystal field. Analysis of the spectra indicates that Eu2+ occupies two types of crystallographic sites (independent interstitial sites of different sizes and shapes in the NZP framework structure). Codoping with Eu and Sm has ensured luminescence with chromaticity coordinates approaching those of white light: (x = 0.27, y = 0.34).

Synthesis, luminescence, and biocompatibility of calcium- and lanthanide-containing NaZr2(PO4)3-type compounds by A. I. Orlova; A. E. Kanunov; E. N. Gorshkova; A. N. Shushunov; S. N. Pleskova; E. R. Mikheeva; D. O. Savinykh; E. S. Leonov (89-94).
Ca0.5Zr2(PO4)3:Er/Yb and Ca0.75Zr2(PO4)2.5(SiO4)0.5:Er/Yb compounds have been prepared and their luminescence properties and biocompatibility have been investigated. We found synthesis conditions that ensured phase homogeneity and formation of nanopowders. Their luminescence properties have been studied. Under IR excitation, emission was observed at λ = 0.525 μm. Cells (neutrophil granulocytes) were shown to retain viability in the presence of the compounds studied.

Preparation of powders and films of the lithium ion conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 by G. B. Kunshina; O. G. Gromov; E. P. Lokshin; V. T. Kalinnikov (95-100).
This paper describes a process for the preparation of powders and films of the lithium ion conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 from peroxide solutions. The use of peroxide solutions ensures the preparation of Li1.3Al0.3Ti1.7(PO4)3 with a room-temperature electrical conductivity of (4–5) × 10−4 S/cm by calcining a precursor at 800°C. The synthesized Li1.3Al0.3Ti1.7(PO4)3 powders were characterized by X-ray diffraction, thermal analysis (DTA/TG), and ionic and electronic conductivity measurements. The growth of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte films is described.

Electrical properties of LiNbO3〈RE〉 crystals grown under steady-state and transient conditions by M. N. Palatnikov; N. V. Sidorov; O. B. Shcherbina; V. A. Sandler (101-108).
The static piezoelectric and dielectric properties and electrical conductivity of LiNbO3〈RE〉 crystals grown under steady-state and transient conditions have been studied in the temperature range ∼290–490 K and in a wide frequency range. The magnitude of the observed anomalies in the electrical characteristics of the crystals and the kinetics of the underlying processes are determined by the micro- and nanodomain structures of the samples.

Magnetic properties of nickel ferrite nanoparticles prepared using flotation extraction by Yu. A. Mirgorod; N. A. Borshch; V. M. Fedosyuk; G. Yu. Yurkov (109-114).
A method has been proposed for the preparation of nickel ferrite nanoparticles in a system of direct sodium dodecyl sulfate micelles using ion flotation. Amorphous nickel ferrite nanoparticles with the overall composition xNiFe2O4 · yFe2O3 · zH2O, containing dodecyl sulfate anion impurities, have been prepared. According to transmission electron microscopy results, the size distribution of the synthesized nanoparticles has a maximum in the range 4 to 6 nm, and the ferrite is X-ray amorphous. The blocking temperature of the synthesized nanoparticles is 25 K. The ferrite possesses superparamagnetic properties, with a specific saturation magnetization of 15 A m2/kg at 5 K.