Inorganic Materials (v.46, #6)

Pressure, temperature, and magnetic-field effects on the transport properties of Cd0.7Mn0.3GeAs2 by A. Yu. Mollaev; I. K. Kamilov; R. K. Arslanov; U. Z. Zalibekov; T. R. Arslanov; E. S. Ibaev; V. M. Novotortsev; S. F. Marenkin (571-573).
The resistivity, Hall coefficient, and magnetoresistance ratio of the ferromagnetic semiconductor Cd0.7Mn0.3GeAs2 have been measured as functions of pressure, temperature, and magnetic field. The ρ(p) and R H(p) curves point to a structural insulator-metal phase transition under both increasing and decreasing pressure. The temperature dependences of ρ and R H show anomalies, which are interpreted as a ferromagnetic-paramagnetic phase transition. Cd0.7Mn0.3GeAs2 is shown for the first time to have a negative magnetoresistance under pressure.

CdSb, ZnSb, and Cd x Zn1 − x Sb low-symmetry crystals: Chemical bonding and technological aspects by A. A. Ashcheulov; I. V. Gutsul; O. N. Manyk; T. O. Manyk; S. F. Marenkin (574-580).
Chemical bonding theory is used to examine fine details of the melting and crystallization behaviors of CdSb, ZnSb, and CdSb-ZnSb solid solutions and to identify conditions for the preparation of these materials with tailored properties.

Mn2 − x Zn x Sb (0.6 ≤ x ≤ 1.0) solid solutions are shown to undergo magnetic phase separation (coexistence of two magnetic phases in a structurally homogeneous material) using a combination of characterization techniques (magnetometry, X-ray diffraction, neutron diffraction, Mössbauer spectroscopy, and resistivity measurements). A model is presented for the coexistence of two magnetic phases in the two-sublattice ferrimagnet Mn2Sb diamagnetically diluted with zinc.

X-ray dosimetric properties of vapor-grown CdGa2S4 single crystals by S. N. Mustafaeva; M. M. Asadov; D. T. Guseinov (587-589).
CdGa2S4 single crystals have been grown from a presynthesized source material by closed-tube iodine vapor transport, and their X-ray dosimetric properties have been studied. Their X-ray sensitivity coefficient K ranges from K = 1.26 × 10−11 to 1.39 × 10−10 A min/(V R) at effective X-ray hardnesses V a = 25–50 keV and dose rates E = 0.75–78.05 R/min, and increases with X-ray dose. The K(V a) curve has a negative slope, in contrast to the K(E) curve. The photocurrent-dose curves of the CdGa2S4 single crystals demonstrate that the steady-state X-ray photocurrent is a power-law function of X-ray dose rate: ΔI E,0E α . With increasing V a, the slope of the curves sharply decreases and α approaches unity.

Phase relations in the Ag8SnS6-Ag2SnS3-AgBr system and crystal structure of Ag6SnS4Br2 by A. G. Mikolaichuk; N. V. Moroz; P. Yu. Demchenko; L. G. Akselrud; R. E. Gladyshevskii (590-597).
The T-x phase diagram of the Ag-Sn-S-Br system has been studied in the composition region Ag8SnS6-Ag2SnS3-AgBr, and a compound of composition Ag6SnS4Br2 has been identified. Ag6SnS4Br2 has a new structure, closely related to that of Ag6GeS4Br2: sp. gr. Pnma, a = 6.67050(10), b = 7.82095(9), c = 23.1404(3) Å, Z = 4, R B = 0.0519, R wp = 0.0782, χ2 = 1.36.

Structure and electrical conductivity of selenium-ion-implanted CdSe films by A. N. Georgobiani; B. N. Levonovich; I. Kh. Avetisov (598-600).
We have studied the effect of annealing on the spectral and photoelectric properties of polycrystalline CdSe films produced by thermal evaporation and implanted with Se ions to doses from 5 × 1015 to 5 × 1016 cm−2. The results demonstrate that, when cadmium vacancies and selenium interstitials are major defects, annealing leads to the formation of microcrystalline two-phase layers during recrystallization, which have low p-type conductivity due to a shallow acceptor at E v + 0.04–0.05 eV, related to interstitial selenium.

Intrinsic photoconductivity of InSe by A. G. Kyazym-zade; V. M. Salmanov; A. A. Salmanova; A. M. Alieva (601-603).
The intrinsic photoconductivity of InSe layered crystals has been measured. The behavior of the photoconductivity at high photon energies can be accounted for by the influence of hyperbolic excitons generated by the laser light.

Growth, structure, and thermal expansion anisotropy of FeIn2Se4 single crystals by I. V. Bodnar; I. A. Viktorov; S. A. Pavlyukovets (604-608).
Single crystals of the ternary compound FeIn2Se4 have been grown by directional solidification in a vertical Bridgman geometry, and their composition, structure, and melting point have been determined. The relative length change of FeIn2Se4 has been measured on a dilatometer using oriented single-crystal samples, and its thermal expansion coefficients have been determined. The thermal expansion of FeIn2Se4 is shown to be markedly anisotropic.

Phase equilibria in the systems AgInSe2-HgIn2Se4 and AgInSe2-HgSe by V. R. Kozer; O. V. Parasyuk; I. D. Olekseyuk (609-613).
The equilibrium phase diagrams along the AgInSe2-HgIn2Se4 and AgInSe2-HgSe joins of the ternary system Ag2Se-HgSe-In2Se3 have been constructed using X-ray diffraction and differential thermal analysis. Both joins are pseudobinary, with eutectic phase diagrams (type V in Roseboom’s classification). The eutectics are located at ≃30 mol % HgIn2Se4 (melting point of 1000 K) and ≃54 mol % HgSe (993 K), respectively. Both systems have considerable terminal solid-solution ranges.

Preparation of titanium diboride nanopowder by S. E. Kravchenko; V. I. Torbov; S. P. Shilkin (614-616).
We have studied the reaction between NaBH4 and TiCl4 at elevated temperatures in the range 570–1020 K and pressures of up to 10 MPa, with no solvent. The results indicate that nanoparticulate titanium diboride forms at temperatures above 820 K. According to electron microscopy data, the titanium diboride powder obtained at 1020 K consists of spherical particles 35–50 nm in diameter, in reasonable agreement with the equivalent particle diameter of ≃45 nm evaluated from the specific surface area of the TiB2 and with the crystallite size D hkl ≃ 30 nm evaluated from X-ray diffraction data.

Effect of laser processing on the dynamic magnetic properties of amorphous Fe64Co21B15 ribbons by A. L. Semenov; A. A. Gavrilyuk; A. V. Gavrilyuk; A. V. Semirov; A. N. Malov; B. V. Gavrilyuk; N. V. Turik; A. Yu. Mokhovikov (617-623).
We have studied the effect of laser processing conditions on the dynamic magnetic properties of amorphous Fe64Co21B15 ribbons. The results indicate that the laser beam scan speed and direction on the sample surface relative to the axis of rolling play a key role in determining the variation of the relative dynamic magnetic permeability with magnetic field and its sensitivity to elastic tensile stress.

We report the optical and electrical properties of a-Si:H and a-Si1 − x C x :H (x = 0.06, 0.17, 0.25,0.32) amorphous films produced by plasma deposition at constant hydrogen content. IR absorption data are used to evaluate the density of Si-H and C-H bonds and the hydrogen concentration in the films. The activation energy for conduction and the carrier mobility in the films are determined from the temperature dependence of their electrical conductivity.

Structural and phase transformation behaviour of electroless Ni-W-Cr-P alloy coatings on stainless steel by Yong Jin; Jing Fan; Ke Mou; Xuejuan Wang; Qun Ding; Yuan Li; Chunmei Liu (631-638).
Ni-W-Cr-P alloy coatings were prepared by electroless deposition on stainless steel. The effects of heat-treatment on the structure and phase transformation behavior, microhardness of the Ni-W-Cr-P alloy coatings were mainly investigated. XRD analysis shows that as-deposited Ni-W-Cr-P coatings were microcrystalline; the precipitation of Ni3P was observed at the annealing temperature of 400°C; after heat-treatment at 500°C the crystallization of Ni3P and Ni was near completion; at 600°C new phase Cr1.12Ni2.88 was observed and Ni3P began to decompose. Cr1.07Fe18.93 and Ni17W3 were formed when heated at 700°C, and Ni3P was not found. With increasing temperature to 800°C, FeNi2P and Cr4Ni15W were the only two dominant phases. The experimental results reveal that with an increase in the annealing temperature, micro-hardness of the Ni-W-Cr-P alloy coatings increased, reached the maximum value at 700°C, and then decreased slightly. Annealing temperature dependence of the microhardness and corrosion resistance of the coatings was also observed. The related strengthening mechanism in the electroless deposited Ni-W-Cr-P alloy coatings is also discussed.

Low-temperature persistent afterglow in opal photonic crystals under pulsed UV excitation by V. S. Gorelik; A. A. Esakov; I. I. Zasavitskii (639-643).
Excitation of synthetic opal with 337.1-nm nitrogen laser pulses gives rise to a persistent afterglow, lasting 15 s at 10 K. The afterglow spectrum correlates with the emission spectrum of opal observed earlier under excitation with UV light-emitting diodes. The effect can be understood in terms of the peaks in the density of photon states near the edges of the photonic band gap in photonic crystals.

Sonocatalytic damage of composite TiO2/ZnO powder to bovine serum albumin under ultrasonic irradiation by Jun Wang; Shixian Wang; Bin Liu; Ying Guo; Liqun Zhang; Xia Chen; Rui Xu; Xiangdong Zhang (644-650).
The composite TiO2/ZnO was prepared by mixing nano-sized TiO2 and ZnO powders directly, in the molar proportion of 4:6, followed by heat-treatment at 500°C for 40 min. The products were charactered by powder X-ray diffraction and transmission electron microscopy. The test of sonocatalytic activities of the composite TiO2/ZnO powders was carried out through the damage of bovine serum albumin (BSA). Otherwise, the effects of several factors on the damage of BSA molecules were evaluated by means of UV-vis and fluorescence spectra. It was found that the damage degree was aggravated with the increase of ultrasonic irradiation time and composite TiO2/ZnO addition amount. These research results were of great significance for driving sonocatalytic method to treat tumor in clinic application.

Morphology and structure of magnetic spheres based on hematite or spinel and glass by V. V. Zyryanov; S. A. Petrov; A. A. Matvienko (651-659).
Magnetic spheres of various origins, isolated from fly ashes of the main Russian thermal coals, have been studied by electron microscopy, optical microscopy, X-ray diffraction, and Mössbauer spectroscopy. The magnetic spheres differ in morphology and have the form of multilevel core-shell nanocomposites, with a hematite or spinel Fe-rich core and a Fe-containing silicate glass shell. We have derived structural formulas of the spinels, which are consistent with all our experimental data. The most promising application fields of such magnetic spheres, after proper selection and modification, are catalysis and composites.

Generalized equations of heterogeneous kinetics are derived which can be used to calculate kinetic parameters of oxide dissolution. Main rate equations are obtained, and their applicability to iron(III) oxide dissolution in sulfuric acid solutions is examined. The dependences of the specific dissolution rate on acid concentration, pH, and temperature are found. Kinetic curves represented as plots of α against t/t 0.5 (where α is the fraction of oxide dissolved at time t and t/t 0.5 is the time needed to dissolve 50% of the sample) are shown to be invariant to the kinetic parameters and the model of dissolution.

Anion disorder in LnF3 (Ln = La, Ce, Pr) crystals by V. F. Krivorotov; P. K. Khabibullaev; Kh. T. Sharipov (668-672).
The mechanism of lattice “melting” in tysonite-structure superionic trifluorides is analyzed in relation to the structure of LaF3 crystals. The ion displacements within the unit cell are shown to correlate with the dynamics of the Raman scattering parameters of the crystals. The frequency and intensity of the lines at 370, 392 (LaF3), 376, and 404 cm−1 (PrF3) show anomalous behavior in three temperature ranges: 160–180, 240–280, and 420–460 K. The anomalies in the two higher temperature ranges are due to lattice disordering in the superionic transition region. The scattering in the range 160–180 K is tentatively attributed to fluoride ion displacements in split sites with a few potential wells. It is shown based on a split-site model that the thermally activated formation of interstices comparable in size to the mobile fluoride ion is an inherent feature of the LnF3 structure.

Hydrochemical synthesis of AgCl x Br1 − x solid solutions by A. A. Grebneva; N. K. Bulatov; L. V. Zhukova (673-678).
A phase-component model is proposed for the hydrochemical conversion of silver chloride to AgCl x Br1 − x solid solutions, and the corresponding quantitative relations are derived. Experimental data are used to obtain a relation between the equilibrium composition of solid solutions and that of the liquid phase at different temperatures. The possible mechanisms of solid-solution formation are considered.

In this letter a simple wet-chemical route was developed to prepare silver nanostructures. The formation of the silver nanostructures occurs in a single process, carried out by mixing an AgNO3 aqueous solution and a para-phenylenediamine solution at room temperature without the introduction of other reducing agents and morphology controlling agents. It is found that both the morphology and the size of such silver nanostructures can be facilely controlled by the molar ratio and concentration of the reactants as well as the solvent that was used to dilute para-phenylenediamine aqueous solution. As-formed silver nanostructures were examined by scanning electron microscopy.

Effect of high-intensity light on the micro- and nanostructuring and thermal expansion of Ta2O5 and Nb2O5 ceramics by M. N. Palatnikov; O. B. Shcherbina; A. A. Frolov; V. N. Pavlikov; M. V. Karpets; O. V. Makarova; N. V. Sidorov; V. T. Kalinnikov (683-690).
This paper examines the effect of exposure to high-intensity light on the formation of fractal micro- and nanostructures and the thermal expansion of tantalum pentoxide and niobium pentoxide ceramics. After such processing, the thermal expansion curve of Ta2O5 shows anomalous regions of zero or negative expansion, whereas the thermal expansion of Nb2O5 ceramics decreases in magnitude in the region of negative values, and their thermal expansion curve becomes more symmetrical.

Erratum to: “Synthesis of Silver Chromate Nanoparticles: Parameter Optimization Using Taguchi Design” by R. Fareghi Alamdari; S. S. Hajimirsadeghi; I. Kohsari (691-691).