Sh. M. Ismailov

Thermophysical Properties of Sulfides of Lanthanum, Praseodymium, Gadolinium, and Dysprosium

The temperature dependence of the thermal conductivity, electrical conductivity, thermoelectromotive force, and thermal expansion coefficient for sulfides of lanthanum, gadolinium, praseodymium and dysprosium of the composition Ln3 – xVxS4 is investigated in the temperature range from 300 to 1200 K. It is shown that the transfer phenomena and thermoelectrical properties of the investigated compositions depend on the concentration of current carriers, cation vacancies, and mobility. Gadolinium sulfide is found to have the highest thermoelectrical efficiency. The scattering from ions of rare-earth elements has a noticeable effect on the magnitude and temperature dependence of the lattice thermal conductivity and electrical resistance.

Thermal and Electrical Properties of Gadolinium Sulfides at High Temperatures

A study is made into the temperature dependence of the thermal conductivity, electrical conductivity, thermoelectromotive force, thermal expansion coefficient, and heat capacity in the temperature range from 300 to 1200 K for polycrystalline gadolinium sulfides GdSy(y= 1.495–1.487) produced both by recrystallization pressing and by crystallization from a melt. The role of the mechanisms of heat and charge transfer is estimated depending on the composition. The reasons for changes in their electrical and thermal properties are analyzed. The thermoelectric efficiency is calculated. It is demonstrated that Z≥ 0.6 × 10–3K–1at T≥ 1000 K.

Thermoelectric and photoelectric properties of the p-n CuInSe2/CdS heterostructures obtained by the quasi-equilibrium deposition method

Through deposition of CuInSe2 films on CdS substrates in a quasi-closed-circuit “hot-wall” reactor, p-n CuInSe2/CdS heterostructures were obtained. The thermoelectric power, current-voltage characteristics, and photosensitivity spectra of the structures were investigated.

The Debye temperature and Grüneisen parameter of the CaLa2S4-La2S3 system

The thermal expansion coefficient of solid solutions in the CaLa2S4-La2S3 system at a temperature of 300 K is investigated experimentally. The Debye temperature, the Grüneisen parameter, and the isothermal compressibility coefficient of solid solutions in the system under investigation are determined from the experimental thermal expansion coefficient. It is demonstrated that, upon substitution of calcium ions for cation vacancies in La2S3, the Debye temperature decreases, the isothermal compressibility coefficient increases, and the Grüneisen parameter remains constant for all compositions in the CaLa2S4-La2S3 system. A correlation between the ionic radii of Ca2+ and La3+, the concentration of cation vacancies, and the rigidity of the lattice, on the one hand, and the Debye temperature, the Grüneisen parameter, and the isothermal compressibility coefficient, on the other, is revealed for the studied samples.

Thermal Conductivity, Thermal Expansion, and Microhardness of CaLa2S4–La2S3 Solid Solutions

The thermal conductivity, thermal expansion, and microhardness of CaLa2S4–La2S3 solid solutions were measured. The increase in thermal expansion in going from La2S3 to CaLa2S4 was shown to correlate with the variation in bond strength. The thermal conductivity and microhardness were found to vary nonmonotonically, which was interpreted in terms of the defect structure of the solid solutions. The estimated thermal shock resistance of the solid solutions passes through a maximum around 70 mol % La2S3 .

Thermal conductivity of silicon carbide ceramics doped with beryllium oxide

The thermal conductivity of silicon carbide ceramics containing up to 3 wt % BeO was measured in the temperature range 300–1300 K. The effective thermal conductivity was found to rise notably with increasing BeO content in the range 1.3–1.5 wt % BeO and to decrease exponentially with increasing porosity.

Influence of heat treatment on the electrophysical properties of thin films of copper-indium diselenide

An investigation of the structural, electrical, optical, and thermophysical properties is carried out on thin polycrystalline films of the ternary semiconductor CuInSe2, which is potentially useful for fabricating solar cells. The thin films were obtained by thermal evaporation of CuInSe2 and Se powder from two independent sources and by high-vacuum deposition in a closed cell (quasiequilibrium deposition). The influence of annealing in air on the parameters of the thin films is analyzed, and the dynamics of variation in the properties of the films are investigated as a function of the annealing time. Temperature dependences of the electrical conductivity, mobility, and thermal conductivity of CuInSe2 thin films are given together with the spectral dependence of the short-circuit photocurrent of a photosensitive Au-CuInSe2-Au structure.

Temperature and pressure dependences of the thermal conductivity of As2(Se1-xTex)3 solid solutions

The effect of temperature and pressure on the thermal conductivity of solid solutions based on the As2(Se1 - xTex)3 system was investigated in glassy and polycrystalline samples at 273–450 K and hydrostatic pressures of up to 0.35 GPa. The compound As2Se3 was studied in a temperature range of 300–760 K. Analysis showed that the short-cange order structure in As2Se3 remains unchanged upon the glass—liquid transition right up to 760 K.

The effect of temperature and pressure on the heat conductivity of TlSbC2VI (CVI → S, Se, Te)

The effect of temperature and pressure on heat conductivity of ternary compounds TiSbC2VI (CVI → S, Se, Te) in the solid and liquid states in a temperature range of 300–800 K, as well as under the pressure up to 0.35 GPa in a temperature range of 275–450 K, is studied. The dependence of heat conductivity on average atomic weight under the S → Se → Te transition is found. Analysis of the experimental data makes it possible to attribute TlSbS2 to the class of substances exhibiting semiconductor-semiconductor melting behavior.

Dynamic effects during thermoelastic martensitic transformations in TiNiCu alloys

Spontaneous periodic oscillations in the phase transformation rate during a system evolution toward a stationary state are observed in TiNiCu alloys. The conditions of manifestation and amplification of these oscillations are established and possible applications of this phenomenon are considered.