The linear coefficient of thermal expansion and the Debye temperature of PbTe in the high-temperature range have been investigated using X-ray diffractometry. The studies were carried out on samples of two types: single crystal and PbTe powder, synthesized separately. Both types of samples showed fairly similar results in all measurements. It has been established that in the temperature range 293-773 K the linear thermal expansion coefficient is constant and for powder: 20.1*10-6 +/- 0.9* 10-6 K-1 and for single crystal: 19.7*10-6 +/- 0.8*10-6 K-1. The Debye temperature measured in the temperature range 293-573 K equal to 105 +/- 3 K.

The values of the lattice period and the linear coefficient of thermal expansion (α) of Pb 1-x Cd x Te solid solutions are determined depending on the cadmium content and temperature using high-temperature X-ray diffractometry. An increase in the concentration of cadmium in Pb 1-x Cd x Te in the range x=0.02-0.08 leads to a significant increase in the linear coefficient of thermal expansion. A change in temperature range T=293-673 K leads to decrease in the linear coefficient of thermal expansion. Besides, an increase in temperature does not affect the value α of the undoped PbTe in the indicated temperature range. Keywords: lead telluride, cadmium, solid solutions, lattice period, linear coefficient of thermal expansion.

The linear coefficient of thermal expansion and the Debye temperature of PbTe in the high-temperature range have been investigated using X-ray diffractometry. The studies were carried out on samples of two types: single crystal and PbTe powder, synthesized separately. Both types of samples showed fairly similar results in all measurements. It has been established that in the temperature range 293-773 K the linear thermal expansion coefficient is constant and for powder: α=20.1· 10 -6 ± 0.9· 10 -6 K -1 and for single crystal: α=19.7· 10 -6 ± 0.8· 10 -6 K -1 . The Debye temperature measured in the temperature range 293-573 K equal to 105±3 K Keywords: lead telluride, linear thermal expansion coefficient, Debye temperature.

The values of the lattice period and the linear coefficient of thermal expansion (alfa) of Pb1-xCdxTe solid solutions are determined depending on the cadmium content and temperature using high-temperature X-ray diffractometry. Аn increase in the concentration of cadmium in Pb1-xCdxTe in the range x = 0.02–0.08 leads to a significant increase in the linear coefficient of thermal expansion. A change in temperature range T = 293–673 K leads to decrease in the linear coefficient of thermal expansion. Besides, an increase in temperature does not affect the value alfa of the undoped PbTe in the indicated temperature range.

Nanocrystalline PdO films have been characterized by X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. The results demonstrate that thermal oxidation in an O2 atmosphere causes ~35-nm-thick nanocrystalline Pd films on SiO2/Si(100) substrates to undergo a sequence of phase transformations resulting in PdO formation, followed by PdO decomposition into metallic Pd at T > 1120 K. In the range 670–970 K, the a and c tetragonal cell parameters of the nanocrystalline PdO films increase monotonically with increasing temperature. The present and previously reported data have been used to construct a model for the unit cell in the crystal structure of palladium(II) oxide. Based on the quasi-chemical approach, we propose a model that accounts for the observed increase in the tetragonal cell parameters and the p-type conductivity of the nanocrystalline PdO films in terms of the formation of excess interstitial oxygen atoms.

В настоящей работе предложена новая методика построения решетки совпадающих узлов для ОЦК и ГЦК кристаллов. Получены условия образования орторомбической, тетрагональной и кубической решетки совпадений и указаны конкретные решетки этих сингоний. Показаны возможные поликристаллические структуры, имеющие общую решетку совпадающих узлов.

According to high-temperature differential mass spectrometry, analytical form of the dependence of structure of the saturated vapor composition over melts of the system Ga–Pb on partial pressures of components and total pressure in the system was determined. On the basis of this dependence, taking into account corrections for the deviations from thermodynamic equilibrium conditions in the reaction cell, the scientifically-proved method of the synthesis of Ga y Pb1–y (y = 0.002–0.050) films with precision control over their quantitative composition structure was developed.

From the data of reflectance measurements for Pb 1 − x Ag x Te ( x = 0.001–0.007) alloy single crystals, the hole concentration and conductivity are calculated as functions of the Ag content. It is established that, for all of the samples, the plasma minimum is in the infra-red region and shifts to shorter wavelengths, as the Ag content is increased. In this case, the hole concentration and conductivity increase.

Microdeformations of the crystal lattice of PbTe1 − x Br x solid solutions depending on the bromine content are determined by analysis of the physical broadening of X-ray reflections. It is found that they increase with the introduction of bromine from 0.188% (for undoped PbTe) to 0.283% for PbTe1 − x Br x at x = 0.02. The microstrains remain constant with a further increase in the bromine content.

The experimental results, which have been received during the examination of the crystal structure and electronic properties of PbTe/Si heterostructures doped with Ga by means of two different techniques, are systematised in this study. The first doping procedure is based on the two-zone annealing of previously formed by modified HWE technique PbTe/Si heterostructures in the saturated vapour which corresponds to the three-phase equilibrium L1-GaTe(S)-V in Ga-Te binary system. The second method of preparation of PbTe〈Ga〉/Si heterostructures offers the direct one stage synthesis, in which the doping and the layer condensation processes proceed simultaneously. The experimental results clearly demonstrate the different character in the charge carrier densities evolutions with the Ga impurity concentration for PbTe〈Ga〉/Si films prepared by these techniques. The measurements of conductivity and Hall coefficient have shown that Ga atoms behave as the donor impurities only in PbTe〈Ga〉/Si films with little excess of Te, which were fabricated by vapour phase doping. On the contrary, in PbTe〈Ga〉 films prepared by a direct one-stage synthesis the character of electrical activity of Ga impurities depends upon both the concentration and the deviation from stoichiometry. It has been found that the Pb1−yGayTe1+δ films with yGa>0.015, which are heterogeneous and consist of two (PbTe+GaTe) or three phases (PbTe+GaTe+Ga2Te3) have the best sensitivity to IR radiation. In the scope of quasi chemical approach it is possible to explain the complicated amphoteric behaviour of Ga atoms by different mechanisms of substitution (GaPb×, GaPb1− and GaPb1+) or implantation (Gai3+) of impurity atoms in the PbTe crystal structure.

The thermopower coefficient α0 and the electrical conductivity σ of Pb1 − x Ag x Te solid solutions, where x = (0–0.007), are measured at T = 300 K. The hole concentration p is calculated. All samples are of the p type. With increasing silver content, α0 decreases, while p and σ increase. For undoped crystals, α0 = 251.0 μV/K, p = 1.1 × 1018 cm−3, and σ = 165 Ω−1 cm−1. At the silver-solubility limit for x = 0.007, α0 = 193.8 μV/K, p = 2.3 × 1018 cm−3, and σ = 216 Ω−1 cm−1. The hole concentration in all samples is much lower than the concentration of introduced silver atoms. The hole gas in Pb1 − x Ag x Te solid solutions is weakly degenerate in the entire silver-concentration range.

This work is aimed at finding the boundaries of the region of the existence of the solid solutions of Ga in PbTe films prepared on Si substrates with the use of the modified “hot wall” technique. The quantitative results on the composition of the Pb1-y GayTe films with a thickness of more than 1 µm indicate that the gallium concentration yGa in our samples ranges from 0.0004 yGa0.045, depending on the ratio of the partial pressures of the metallic components, which maybe specified by the temperature and composition of the Ga1–xPbx liquid melts. By varying the partial pressures of the metallic components and the chalcogen, we succeeded in synthesizing Pb1-yGayTe layers with a Te concentration ranging from 0.495 to 0.515 mol %. According to the results of a complex investigation with the use of X-ray diffraction, scan ning electron microscopy, and local X-ray spectrum analysis, the region of the existence of homogeneous Pb1 - y GaTe films is substantially narrower than the specified composition range: the limiting Ga concentration in these samples is no more than yGa = 0.011 ± 0.0005. It has been shown that the study of gallium solubility in PbTe should include not merely a quasi-binary PbTe-GaTe section, but also PbTe-Ga2Te3 and PbTe-Ga2Te5 polythermic sections. As indicated by the experimental data, the homogeneity region of the solid solutions of gallium in lead telluride is asymmetric with respect to the quasi-binary PbTe-GaTe section. It has been found that the deviation of the Pb1-yGayTe films from stoichiometry toward excessive concentration of tellurium promotes increased solubility of gallium in the lead telluride matrix.

The solubility of cadmium in PbTe was determined using microhardness and hydrostatic density measurements and by electron microscopy and electron probe microanalysis. All these methods indicate that the existence region of Pb1 − x Cd x Te solid solutions (ss) extends to x = 0.08 at 670°C. As the cadmium concentration of the solid solution increases, microhardness shifts up, whereas density shifts down.

The concentration of free electrons, Fermi level, and specific electric conductivity on the basis of the studied coefficient of IR reflection in the region of plasma resonance of solid solutions PbTe1 − x Br x is determined. It is found that the concentration of electrons grows upon an increase in bromine concentration; however, it is much less than the concentration of the introduced foreign atoms. At x > 0.03, the Fermi level is in the band gap close to the bottom of the conductivity zone at a distance of 0.77 kT, which results in degradation of the semiconductor and constancy of electron concentration and specific electrical conductivity upon a further increase in the dissolved bromine concentration.

Plasma resonance in the IR reflection spectra is used to measure the concentration and relaxation time of free charge carriers along with the conductivity in PbTe 1 − x Cl x solid solutions. It is found that with increasing the chlorine concentration, the electron concentration and conductivity increase and reach saturation at x = 0.03 ( n = 5.5 × 10 19 cm −3 , σ = 3750 Ohm −1 · cm −1 ). The relaxation time decreases with increasing the chlorine concentration and reaches the minimum value of 2.2 × 10 −14 s at x = 0.03; then, it almost does not change.

The crystal lattice period of the Pb1 − x Ag x Te solid solutions is studied as a function of the silver content. The a parameter is found to decrease sharply with an increase in the dopant concentration. The solubility of silver in PbTe corresponds to x = 0.007. A possible mechanism of silver dopant incorporation into the PbTe lattice is considered on the basis of the quantitative interpretation of the obtained data.

Vapor composition and thermodynamic properties of melts of the In-Pb system were studied by high-temperature mass spectrometry. In the temperature range 780–1170 K, the In 1− x Pb x melts feature an appreciable positive deviation from the ideal behavior.

PbTe(Ga) films on Si substrates are obtained from independent sources of tellurium and metal-component vapors by the hot-wall technique. The correlation between the microdeformation of the crystal lattice and the unit-cell parameter is established using an x-ray analysis.

Lattice parameter fluctuations and atomic displacements from equilibrium positions in PbTe 1− x Cl x solid solutions have been studied by x-ray diffraction. Both parameters are shown to increase with chlorine content, reaching 0.026 and 0.045 Å, respectively.