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Phase equilibria in the FeS–Ga2S3–In2S3 system were investigated by differential thermal analysis and X-ray powder diffraction analysis. A number of polythermal sections, the isothermal sections at 900 and 1070 K, and the projection of the liquidus surface of the phase diagram were constructed. It was determined that this system is quasi-ternary, and that the liquidus surface consists of the fields of primary crystallization of six phases. Wide regions of solid solutions based on binary and ternary compounds (FeGa2S4 and FeIn2S4) were found, which are of interest as magnetic materials.

The Bi-Se system was studied by differential thermal analysis, powder X-ray diffraction, scanning electron microscopy, as well as by electromotive forces (EMF) measurements of electrochemical cells (−) Bi (solid) │ionic liquid + Bi3+ │ Bi-Se (solid) ( +). A new refined version of the phase diagram reflecting the compounds Bi2Se3, Bi3Se4, Bi8Se9, BiSe, Bi8Se7, Bi4Se3, and Bi3Se2 with almost constant composition was constructed. It was established that the first compound melts congruently, and all the rest melt with peritectic reaction. The types and parameters of the crystal lattices of the above-mentioned compounds were determined based on the powder diffraction patterns. From the EMF measurements, the partial molar functions of bismuth in alloys and the standard integral thermodynamic functions of bismuth selenides were calculated. Comparative analysis of the obtained results with the literature data is carried out.

The thermodynamic properties of a Bi–Se system are studied within 50–65 at % Se at 300–450 K using electromotive force measurements. The relative partial molar functions of bismuth in alloys are calculated, from which mutually consistent standard Gibbs free energies, enthalpy, and standard entropies are obtained for the compounds Bi2Se3, Bi3Se4, Bi8Se9, and BiSe. The data obtained for Bi2Se3 are compared to those in the literature, and the thermodynamic functions for other compounds are found for the first time.

Solid-phase equilibria in the Tm–Te system and the thermodynamic properties of thulium tellurides are studied via electromotive force (EMF) method and X-ray phase analysis. Experimental data show that compounds TmTe, Tm2Te3, and TmTe3 form in the system. The partial thermodynamic functions of TmTe and Tm in alloys are found for the first time from EMF measurements in concentration cells, relative to TmTe and Tm electrodes at 300–450 K, from which standard thermodynamic functions of formation and standard entropies of intermediate compounds are calculated.

Phase equilibria in the quasi-ternary system Bi2S3–Bi2Te3–BiI3 were studied by differential thermal analysis, X-ray powder diffraction analysis, and scanning electron microscopy. The isothermal sections at 300, 750, 800, and 850 K were constructed, and so were some polythermal sections and a projection of the liquidus surface. The primary crystallization fields and homogeneity regions of phases, and the types and coordinates of in- and monovariant equilibria were determined. It was shown that the system is characterized by the formation of limited regions of solid solutions based on bismuth sulfide and telluride, and also ternary compounds Bi2Te2S, BiSI, and BiTeI.

The existence of the ternary compounds Tl9DyTe6 and Tl4DyTe3 was predicted and their synthesis was performed based on the analysis of structural features of Tl5Te3. It was shown that both compounds are ternary structural analogs of Tl5Te3 (space group I4/mcm) and have the following unit cell parameters of the tetragonal lattices: a = 8.8781(7) A, c = 12.9762(14) A, Z = 2 (Tl9DyTe6) and a = 8.8588(9) A, c = 13.0524(16) A, Z = 4 (Tl4DyTe3). To determine the primary crystallization fields and homogeneity regions of these compounds, phase equilibria in the Tl–Dy–Te system were studied in the composition region Tl2Te–Tl5Te3–Tl4DyTe3. The phase diagrams of various subsystems were constructed and analyzed, namely, the phase diagrams of the lateral constituents Tl5Te3–Tl4DyTe3 and Tl2Te–Tl4DyTe3, some internal polythermal sections, the isothermal section of the phase diagram at 300 K, and projections of the liquidus and solidus surfaces. It was found that the homogeneity region of solid solutions with the Tl5Te3 structure includes the stoichiometric compositions of the compounds Tl9DyTe6 and Tl4DyTe3, and occupies most (more than 90%) of the area of the concentration triangle Tl2Te–Tl5Te3–Tl4DyTe3.

A comprehensive study of solid-phase equilibria in the system Cu-Sb-S and thermodynamic properties of copper antimony sulfides was conducted by the powder x-ray diffraction technique, differential thermal analysis and electromotive forces (EMF) methods. The phase diagram of the system at 300 K constituting Cu3SbS4, CuSbS2, Cu3SbS3, Cu12Sb4S13 and Cu14Sb4S13 ternary compounds was built. Some components of the presented phase diagram differ from the previous works. From the data of EMF measurements of the concentration cells relative to the Cu electrode with a solid electrolyte Cu4RbCl3I2, the partial thermodynamic functions of copper in some phase regions of the Cu-Sb-S system and the standard thermodynamic functions of formation and the standard entropies of the ternary compounds were determined experimentally for the first time.

This work presents new data on the solid-phase equilibria of the Tl-Tb-Te ternary system in the Tl2Te-Tl2Te3-TlTbTe2 composition region and the thermodynamic functions of the TlTbTe2, and Tl9TbTe6 ternary compounds. Studies were carried out by using the electromotive forces method (EFM) and the powder x-ray diffraction technique. From the EMF measurements of the concentration cells of the type (−) TbTe (s) | glycerol + KCl + TbCl3 | (Tb in Tl-Tb-Te alloys) (s) (+) in the 300-450 K temperature interval, the relative partial thermodynamic functions of TbTe and Tb in alloys of the Tl2Te3-TlTe-TlTbTe2, and TlTe-TlTbTe2-Tl9TbTe6 three-phase regions were determined. Based on the solid-phase equilibria diagram, the potential-forming reactions responsible for the indicated partial molar quantities were determined and the standard thermodynamic functions of formation and standard entropies of the TlTbTe2 and Tl9TbTe6 ternary compounds were calculated.

The electrochemical reduction of iron (III) ions into zero-valent iron from a solution of ethylene glycol was accomplished. The kinetics and mechanism of the electroreduction process were investigated by cyclic and linear polarization techniques. The influence of temperature, potential sweep rate, and concentration of iron (III) ions on the electroreduction process was also studied. The observed values of effective activation energy revealed that the investigated electroreduction process is accompanied by mixed kinetics control. Moreover, the results of SEM and X-ray diffraction analysis confirmed the deposition of thin Fe films under the optimized conditions.

The results of studying the Ag–Sb–Se system by measuring the electromotive force (EMF) of concentration cells with the Ag4RbI5 solid electrolyte with respect to silver electrode in the temperature region of 300–450 К are shown. The solid solutions based on the AgSbSe2 form along the section Ag2Se–Sb2Se3 and their homogeneity region is determined. Based on equations of EMF vs. temperature dependences, the partial molar functions of silver in certain phase domains of this system are calculated. The standard thermodynamic functions of formation and the standard entropies are determined for the solid phases Ag0.8Sb1.2Se2.2, Ag0.9Sb1.1Se2.1, and AgSbSe2 and also for the low-temperature modification Ag2Se. The values found for AgSbSe2 and Ag2Se are compared with the literature data.

The Bi–S–Te system has been studied using emf measurements in the composition region Bi2S3–Bi2Te3–Te–S at temperatures in the range 300–450 K. We have calculated relative partial molar functions of bismuth in alloys and used the results to obtain self-consistent sets of the standard Gibbs free energy, standard enthalpy, and standard entropy of the Bi2S3, Bi2Te3, and Bi2Te2S compounds and a solid solution with the composition Bi2Te1.8S1.2, based on the last compound. The data obtained for Bi2S3 and Bi2Te3 have been compared to data available in the literature. The thermodynamic functions of Bi2Te2S and Bi2Te1.8S1.2 have been determined for the first time.

Fundamental thermodynamic properties of the synthetic analog of the famatinite mineral - Cu3SbS4 were studied on the basis of electromotive force (EMF) measurements. The EMF of the concentration chains relative to the Cu electrode with a solid electrolyte was measured for the alloys from the Cu3SbS4 + Sb2S3 + S phase region at 300-380K temperature interval. Based on measurement data, the relative partial thermodynamic functions of copper in alloys, the standard thermodynamic functions of formation, as well as, the standard entropy of the Cu3SbS4 ternary compound were calculated for the first time.

The SnSe–Sb2Se3–Se system was studied by the emf method and X-ray powder diffraction analysis, and the diagram of solid-phase equilibria at 400 K was constructed. The partial thermodynamic functions of SnSe in various phase regions of the studied system were calculated from the measured emf of concentration cells with respect to a SnSe electrode in the temperature range 300–450 K. These data together with the corresponding thermodynamic functions of SnSe and Sb2Se3 were used to calculate the partial molar functions of tin in alloys, and also the standard thermodynamic functions of formation and standard entropies of the compounds SnSe2, Sn2Sb6Se11, SnSb2Se4, and Sn2Sb2Se5.

The Tl–Er–Te ternary system was studied in the Tl2Te–Tl2Te3–TlErTe2 composition region by the emf method and X-ray powder diffractions analysis. The partial thermodynamic functions of ErTe and Er in alloys were determined from the emf measurements. Using the constructed diagram of solid-phase equilibria, the potential-forming reactions responsible for the above partial molar quantities were determined, and the standard thermodynamic functions of formation and standard entropies of the Tl9ErTe6 and TlErTe2 compounds were calculated.

Phase equilibria in the FeSe–Ga2Se3–In2Se3 system were studied by differential thermal analysis and X-ray powder diffraction analysis. A number of polythermal sections, the isothermal section at 1000 K, and the projection of the liquidus surface of the phase diagram were constructed. It was determined that this system is quasi-ternary, and that the liquidus surface comprises the fields of primary crystallization of six phases. The types and coordinates of invariant and monovariant equilibria were found. Wide regions of solid solutions based on binary and ternary compounds (FeGa2Se4, FeIn2Se4) were revealed, being of interest as magnetic materials.

Phase equilibria in the Ag2Te-PbTe-Sb2Te3 system were experimentally investigated by means of differential thermal analysis, powder X-ray diffraction techniques and electromotive force (EMF) measurement method. A liquidus surface projection of the system, 750 K and 300 K isothermal sections, as well as five vertical sections of the phase diagram, were constructed. The primary crystallization fields of phases and homogeneity range of phases were also determined. The character and temperature of the various nonvariant and monovariant equilibria were identified. The studied sys-tem is characterized by the formation of a wide continuous band of a high-temperature cubic structured solid solution (?-phase) between PbTe and Ag1-xSb1 + xTe2 + x intermediate phase. The partial molar thermodynamic functions of lead telluride in alloys and standard integral thermodynamic functions of the ?-solid solutions along the 2PbTe-"AgSbTe2" section were calculated based on the EMF measurements results.

We address the methodology of a complex study of phase equilibria and thermodynamic properties in ternary metal and semiconductor systems using the emf method. A focus is on the behavior of partial molar functions in heterogeneous phase fields in the context of Voronin’s concept of partial heterogeneous functions (PHFs). The applicability criteria of emf measurements in heterogeneous phase fields for thermodynamic calculations have been determined. The scheme for calculating the integral thermodynamic functions (ITFs) of ternary phases from the partial molar functions of one component and the phase diagram using the integration of the Gibbs–Duhem equation has been described. Numerous thermodynamic data for ternary chalcogenide and chalcohalide systems gained by various variants of the emf method are cited.

The phase equilibria in the Cu-Sb-S-I quaternary system were studied by differential thermal analysis and X-ray phase analysis methods in the CuI-SbSI-SbI3 concentration intervals. The boundary quasi-binary section CuI-SbSI, 2 internal polythermal sections of the phase diagram, as well as, the projection of the liquidus surface were constructed. Primary crystallisation areas of phases, types, and coordinates of non- and monovariant equilibria were determined. Limited areas of solid solutions based on the SbSI (b-phase) and high-temperature modifications of the CuI (α1- and α2- phases) were revealed in the system. The formation of the α1 and α2 phases is accompanied by a decrease in the temperatures of the polymorphic transitions of CuI and the establishment of metatectic (3750C) and eutectoid (2800C) reactions. It was also shown, that the system is characterised by the presence of a wide immiscibility region that covers a significant part of theliquidus surface of the CuI and SbSI based phases

The phase equilibria in the ternary Tl-S-I system were investigated experimentally by means of powder X-ray diffraction (PXRD) and differential thermal analysis (DTA). Five isopleth sections, liquidus surface projection and room temperature isothermal section were constructed based on experimental data. dc -and ac -electric properties of the TlS and Tl 6 SI 4 crystals were studied within the temperature and frequency ranges from 120 K to 300 K and from 50 kHz to 35 MHz, respectively. The hopping mechanism for charge transfer over the localized states near the Fermi level was established at low temperatures and high frequencies for these compounds. The density and energy scatter of the states which are located in the vicinity of the Fermi level as well as the average time and distances of jumps were estimated for the title compounds.

In connection with the contradictoriness of literature data, phase equilibria in the Ag–Sn–Se system were restudied by differential thermal analysis and X-ray powder diffraction analysis. A number of polythermal sections and the isothermal section at room temperature of the phase diagram were constructed, and a projection of the liquidus surface was built. The primary crystallization fields of phases and the types and coordinates of in- and monovariant equilibria were determined. It was demonstrated that, in the system, two ternary compounds, Ag8SnSe6 and AgxSn2 – xSe2 (0.84 < x < 1.06), form. The former melts congruently at 1015 K and undergoes a polymorphic transformation at 355 K, and the latter melts with decomposition by a peritectic reaction at 860 K. The formation of the compound Ag2SnSe3, which was previously reported in the literature, was not confirmed. Based on the phase diagrams of boundary binary systems and the results of the differential thermal analysis of a limited number of samples of the ternary system, equations were obtained for calculation and 3D modeling of the liquidus and phase-separation surfaces.

The electrochemical reduction of molybdate ions in tartaric electrolyte has been investigated in this work. Kinetics and mechanism of the electrochemical process have been studied by cyclic and linear voltammetric polarization methods. The effect of the temperature, the rate of potential-scanning and the concentration of the molybdate ions on the electrochemical process has been also studied. By estimating the effective activation energy, it was revealed that the electroreduction process is accompanied by mixing kinetics control.

The paper presents the results of a study of solid-phase equilibria in the Tb–Te system and the thermodynamic properties of terbium tellurides obtained by the methods of electromotive forces and X-ray diffraction analysis. Based on the experimental data, it was established that the TbTe, Tb2Te3, TbTe2 и TbTe3 compounds are formed in the system. For the investigations of the alloys from the two-phase regions TbTe3+Te, TbTe2+TbTe3, and Tb2Te3+TbTe2, the EMF of concentration cells relative to the TbTe electrode was measured. The EMF of concentration cells relative to the terbium electrode was measured for the TbTe+Tb2T3 region. The partial thermodynamic functions of TbTe and Tb in alloys were determined bycombining the EMF measurements of both types in the 300–450 K temperature range, based on which the standard thermodynamic functions of formation and standard entropies of the indicated terbium tellurides were calculated. References1. Jha A. R. 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The process of co-deposition of Ni with Mo from alkaline electrolytes was studied by taking linear and cyclic polarization curves of Pt electrode at various concentrations of initial components and potential scan rates. Solutions of Na2MoO4∙2H2O and NiSO4∙7H2O were used as sources of ions of the main components in NH4OH electrolyte. It was found that co-deposition of nickel with molybdenum goes through the oxide formation stage, and a solid solution of these two metals is deposited on the cathode surface. The film obtained at constant current on Ni electrode under optimal conditions was found amorphous, but additional thermal treatment at 500 °C for one hour made it polycrystalline. This was confirmed by peaks in X-ray diffraction patterns, corresponding to NiMoO4, Ni, and MoO3. The proposed electrolyte and electrolysis conditions allow to obtain thin films with molybdenum content ranging from 17.1 to 50.9 at.%. The co-deposition of Ni with Mo is limited by diffusion of these ions to the cathode surface. The knowledge of the mechanism of co-deposition of Ni and Mo will make possible a selection of optimal conditions for deposition of alloys of the required composition with satisfactory electrocatalytic properties.

The results of a thermodynamic study of the Tl2Te–Tl2Te3–TlGdTe2 system by the electromotive force (EMF) method in the temperature range 300–450 K were presented. The partial thermodynamic functions of GdTe and Gd in alloys were first determined from the experimental EMF data for concentration cells relative to the GdTe electrode. The standard thermodynamic functions of formation and standard entropies of Tl9GdTe6 and TlGdTe2 were calculated based on these data.

The phase equilibria in the ternary Tl–Se–I system have been investigated by means of differential thermal analysis, X-ray powder diffraction and the electromotive force measurements (EMF) of electrochemical cells relative to the thallium electrode with ionic liquid as an electrolyte. Several polythermal sections, the isothermal section at 300 K and the projection of the liquidus surface of the system have been constructed. The homogeneity and primary crystallization regions of intermediate phases, as well as types and coordinates of non- and monovariant equilibria have been determined. Formation of two congruently melting ternary compounds (Tl5Se2I at 720 K, and Tl6SeI4 at 705 K) was observed. It was revealed that the system is characterized by the existence of wide areas of α- (based on Tl2Se) and δ-solid solutions (based on Tl5Se2I). Standard thermodynamic functions of formation and standard entropies of Tl5Se2I and Tl6SeI4 compounds were calculated based on the thermodynamic study of Tl–Se–I alloys by the EMF measurements with an ionic liquid electrolyte.

The present contribution is devoted to the electrochemical deposition of Sb 2 Se 3 thin films from tartrate electrolyte. The study was conducted by potentiodynamic, potentiostatic and galvanostatic methods carried out under different conditions at Pt, Cu and Ni electrodes. The kinetics and mechanism of the electroreduction of antimony and selenite ions in the tartaric acid were studied separately for the electrochemical deposition. Comparison of the obtained polarization curves showed that co-deposition occurs between electroreduction potentials of antimony and selenium, indicating depolarization electrode effect for antimony ions. The influence of electrolyte compo­sition, pH, current density, temperature, etc. has been studied. On the basis of cyclic polarization, X-ray phase and SEM-EDX analyses, it is found that Sb-Se thin films are deposited on Pt and Ni electrodes, but not on Cu electrode. Black, uniform, crystalline and shiny films of the stoichiometric composition of Sb 2 Se 3 compound are deposited on Pt and Ni electrodes within the 338-348 K temperature interval, pH 1.85, current density of 2.5-3.0 A/dm 2 , and annealing temperature of 703 K. Experiments were carried out using the optimal electrolyte composition containing 0.05 M SbOCl + 0.05 M H 2 SeO 3 + 0.007 M C 4 H 6 O 6 .

The solid-phase equilibria and thermodynamic properties of an As–Se system are studied using the electromotive force (EMF). The existence of compounds As2Se3, AsSe, and As4Se3 in a system with near constant composition is confirmed. The relative partial molar functions, standard Gibbs free energies, enthalpies of formation, and standard entropies of As in the alloys are calculated using EMF measurements.

The Tl–I system has been studied using differential thermal analysis, X-ray diffraction, and emf measurements on TlI concentration cells. A more accurate Tl–I phase diagram is presented, according to which the compounds existing in the Tl–I system are TlI, Tl2I3, and TlI3. Thallium monoiodide melts congruently at 715 K and undergoes a polymorphic transformation at 440 K. The other iodides melt peritectically at 535 and 404 K, respectively. In contrast to what was reported previously, no compound of composition Tl3I4 has been obtained. Using experimental emf data, we evaluated relative partial molar thermodynamic functions of the TlI in alloys of the TlI–I system and the standard Gibbs free energy, enthalpy of formation, and standard entropies of TlI3 (−ΔG 298 0 = 142.79 ± 0.73 kJ/mol, −ΔH 298 0 = 135.37 ± 2.85 kJ/mol, and S 298 0 = 263.3 ± 7.4 J/(mol K)) and Tl2I3 (271.39 ± 1.47, 262.40 ± 5.34, and 322.8 ± 13.2).

The solid-phase diagram of the Tl-TlBr-S system was clarified and the fundamental thermodynamic properties of Tl6SBr4 compound were studied on the basis of electromotive force (EMF) measurements of concentration cells relative to a thallium electrode. The EMF results were used to calculate the relative partial thermodynamic functions of thallium in alloys and the standard integral thermodynamic functions (-ΔfG0, -ΔfH0, and S0298) of Tl6SBr4 compound. All data regarding thermodynamic properties of thallium chalcogen-halides are generalized and comparatively analyzed. Consequently, certain regularities between thermodynamic functions of thallium chalcogen-halides and their binary constituents as well as degree of ionization (DI) of chemical bonding were revealed.

The phase relations in the Tl–Te–I system have been experimentally investigated over the entire concentration range mainly by thermal analysis (DTA), X-ray diffraction (XRD) applied to equilibrated alloys. The isothermal section at 300 K, liquidus surface projection and the phase diagrams of the six isopleth sections have been constructed. The homogeneity ranges and primary crystallization fields for the all phases, as well as, the character and temperature of non- and monovariant equilibria were determined in the system. The crystal structure of the Tl5Te2I compound has been determined by single crystal X-Ray diffraction. It is found to be stoichiometric and isostructural which crystallize in the In5Bi3 structure type with four formula units in the tetragonal system, space group I4/mcm, а = 9.001(2); c = 13.291(4) A.

By using differential thermal analysis (DTA), X-ray analysis and electromotive force (EMF) methods the Tl–Se–I system was investigated in the Tl–TlI–Se composition range. Several polythermal sections, the isothermal section at 300 K and the projection of the liquidus surface of the system were constructed. The fields of primary crystallization of phases as well as types and coordinates of non- and monovariant equilibria were determined. Formation of two congruently melting ternary compounds (Tl 5 Se 2 I at 720 K, and Tl 6 SeI 4 at 705 K) was observed. The system is characterized by the existence of wide areas of solid solutions on the base of Tl 2 Se (α-phase) and Tl 5 Se 2 I (δ-phase). The partial molar thermodynamic functions ( Δ G ‾ , Δ H ‾ , Δ S ‾ ) of thallium as well as the standard integral thermodynamic functions of Tl 6 SeI 4 and Tl 5 Se 2 I compounds and Tl 5 Se 3− x I x solid solution (for x = 0.2, 0.4, 0.5, and 0.8) were calculated based on the EMF data.

The Tl5Te3-Tl5Te2Br system has been studied in the temperature range 300–430 K using emf measurements on thallium concentration cells. We have identified a continuous series of solid solutions in the system and determined their partial and standard integral thermodynamic functions.

The equilibrium subsolidus phase diagram of the TlCl-Tl2Se-TlSe system has been mapped out using X-ray diffraction analysis and emf measurements on thallium concentration cells. The Tl5Se2Cl compound has been shown to be a nonstoichiometric phase with a homogeneity region extending over a considerable part of the Tl2Se-Tl5Se2Cl-Tl5Se3 composition triangle. The emf results have been used to evaluate the relative partial thermodynamic functions of the thallium in the alloys studied and the standard integral thermodynamic functions (ΔG 0(298 K), ΔH 0(298 K), and S 0(298 K)) of Tl5Se2Cl and Tl5Se2Cl-based solid solutions.

The Tl–TlI–Te ternary system was investigated by using the DTA and XRD analyses, microhardness and EMF measurements, leading to the construction of important polythermal and isothermal sections as well as the projection of the liquidus surface. Determined were the fields of primary crystallization and the types and coordinates of non- and monovariant equilibria. The system features the formation of continuous solid solutions (δ-phase) between the Tl5Te3 and Tl5Te2I compounds. The homogeneity area of the δ-phase completely covers the Tl5Te2I–Tl5Te3–Tl2Te subsystem. The partial molar thermodynamic functions (ΔG‾,ΔH‾,ΔS‾) of thallium as well as the standard integral thermodynamic functions of the Tl5Te3−xIx solid solution (for various x) were calculated based on the results of the EMF measurements.

This paper describes the phase relationships and ternary solubility of the binary and ternary compounds in the Bi2Se3–Bi2Te3–BiI3 system. Differential thermal analysis (DTA), powder X-ray diffraction (PXRD) and scanning electron microscope equipped with energy dispersive X-ray spectrometer (SEM-EDS) were main tools for experimental investigations of the equilibrated samples of the system. This system is found to be quasi-ternary plane of the quaternary Bi–Se–Te–I system. An isothermal section at 300 K, a liquidus surface projection and four isopleth sections of the system were plotted based on experimental and literature data. The existence of the BiTe1-xSexI solid solutions series (γ1 and γ2) in the wide range of composition of BiSeI–BiTeI section was revealed and characterized. No new quaternary compound was found in the system. The primary crystallization fields and homogeneity range of all the existing phases, as well as character and temperature of all the non- and monovariant equilibria of the system were determined.

The Tl 2 Te–TlBr–TlI system was investigated by means of the DTA and XRD analyses and microhardness and EMF measurements. Several polythermal and isothermal sections and the projection of the liquidus surface were constructed. The fields of primary crystallization, as well as types and coordinates of non- and monovariant equilibriums were determined. It was established that the system is characterized by formation of the continuous solid solution (γ-phase) between the Tl 5 Te 2 Br and Tl 5 Te 2 I (Tl 5 Te 3 structure type) iso-structural compounds. The homogeneity field of γ-phase in the Tl 5 Te 2 Br–Tl 5 Te 2 I section penetrates the Tl 2 Te–Tl 5 Te 2 Br–Tl 5 Te 2 I subsystem and occupies its large part. The partial molar thermodynamic functions ( Δ G ¯ , Δ H ¯ , Δ S ¯ ) of thallium were calculated for the Tl 5 Te 2 Br x I 1− x (for x = 0.2; 0.4; 0.6; 0.8) solid solution based on the results of the EMF measurements.

The experimental results on the frequency dependences of the dielectric characteristics and conductivity of the grown Tl6SI4 crystals have allowed revealing the nature of the dielectric losses and the hopping mechanism of charge transfer, estimating the parameters of localized states in the band gap, including the density of states near the Fermi level and their energy scatter, the average hopping time, the average hopping length, and the density of deep traps responsible for the alternating-current (ac) conductivity.

The phase relations in the Tl–Te–I system have been experimentally investigated over the entire concentration range mainly by thermal analysis (DTA), X-ray diffraction (XRD) applied to equilibrated alloys. The isothermal section at 300 K, liquidus surface projection and the phase diagrams of the six isopleth sections have been constructed. The homogeneity ranges and primary crystallization fields for the all phases, as well as, the character and temperature of non- and monovariant equilibria were determined in the system. The crystal structure of the Tl5Te2I compound has been determined by single crystal X-Ray diffraction. It is found to be stoichiometric and isostructural which crystallize in the In5Bi3 structure type with four formula units in the tetragonal system, space group I4/mcm, а = 9.001(2); c = 13.291(4) A.

Phase equilibria in the Tl-TlI-S composition region of the Tl-S-I system were studied by differential thermal analysis, x-ray powder diffraction, and measurements of the microhardness and the emf of concentration circuits relative to a thallium electrode. A series of polythermal sections, an isothermal section at 300 K, and a projection of the liquidus surface were constructed. Primary crystallization regions of six phases, including the ternary compounds Tl6SI4 and Tl3SI, were outlined, and the types and coordinates of non- and monovariant equilibria were determined. It was shown that the ternary compound Tl6SI4 forms tie lines with Tl, TlI, Tl2S, Tl4S3, and TlS in the subsolidus region and that the homogeneity region of Tl6SI4 below 400 K does not exceed 1 mol %. From the emf measurement data, the standard thermodynamic functions of formation and standard entropy of the compound Tl6SI4 were calculated: G ,298 0 = −601.7 ± 2.5 kJ/mol, ΔH ,298 0 = −595.1 ± 4.0 kJ/mol, and S 298 0 = 672 ± 10 J/(mol K).

Phase equilibria in the Ag2Te-PbTe-Bi2Te3 quasi-ternary system were studied by differential thermal analysis, X-ray powder diffraction, and measurements of microhardness and emf of concentration circuits with an Ag4RbI5 solid electrolyte. Some polythermal sections and isothermal (600 and 800 K) sections of the phase diagram, and also a projection of the liquidus surface were constructed. The primary crystallization fields of phases were determined, and the types and coordinates of invariant and monovariant equilibria were found. The system is characterized by the formation of a wide continuous band of high-temperature solid solutions (γ phase) with a cubic structure along the PbTe-AgBiTe2 section. With decreasing temperature (T ≤ 715 K), AgBiTe2 and γ solid solutions, close in composition to this compound, experience solid-phase decomposition to form Bi2Te3, ternary tetradymite-like phases of the PbTe-Bi2Te3 boundary system, and the low-temperature phase of Ag2Te.

Phase equilibria in the Tl5Te3-Tl9BiTe6-Tl5Te2Br system were studied by differential thermal analysis, X-ray powder diffraction, and measurements of microhardness and also emf relative to a thallium electrode. Polythermal and isothermal sections of the phase diagram at 760 and 800 K, and projections of the liquidus and solidus surfaces were constructed. The unit cell parameters, microhardness, and emf in the alloys were described as functions of concentration. The system is characterized by the formation of complete solid solutions with the Tl5Te3 structure.

The Pb-Bi-Te system has been studied in the composition region PbTe-Bi2Te3-Te at temperatures from 300 to 430 K using emf measurements on reversible concentration cells of the type $$( - )PbTe(s)|liquid electrolyte, Pb^{2 + } |(Pb - Bi - Te)(s)( + ).$$ . The subsolidus phase diagram inferred from the emf data includes the ternary compounds PbBi6Te10, PbBi4Te7, Pb2Bi6Te11, and PbBi2Te4 of the nPbTe · mBi2Te3 homologous series. Best fit equations for the temperature-dependent emf data were used to determine the partial thermodynamic functions (\(\overline {\Delta G} \), \(\overline {\Delta H} \), and \(\overline {\Delta S} \)) of the PbTe in the alloys. Using these partial molar functions, subsolidus phase diagram data for the PbTe-Bi2Te3-Te system, and relevant data for PbTe and Bi2Te3, we calculated the standard thermodynamic functions of formation and standard entropies of the above ternary compounds.