I. I. Aliev

Phase equilibria in the Ag2Te-PbTe-Bi2Te3 system

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 equilibrium in the As2S3-TlSe system

The interaction between the components of the As2S3-TlSe system has been studied using diffeential thermal analysis, powder X-ray diffraction, microstructure examination, and microhardness and density measurements. Two new quaternary compounds, TlAs2S3Se and Tl3As2S3Se3, are formed in the system. Both compounds may be prepared in a glassy state. They melt congruently at 350 and 280°C, respectively. The section As2S3-TlSe is a stable diagonal of the ternary reciprocal system As,Tl ‖ S, Se. The As2S3-base solid solution extends to 1.5 mol % TlSe. The extent of the TlSe-base solution is 5.2 mol % As2S3. Under slow cooling, the glass field in the system extends to 85 mol % TlSe; when the system is quenched to liquid nitrogen, the extent of the glass field is 100 mol % TlSe.

Physicochemical study of the Sb2Se3-Ho2Se3 system

The chemical interaction in the Sb2Se3-Ho2Se3 system was studied by physicochemical analysis methods (by differential thermal, X-ray powder diffraction, and microstructural analyses and also by density and microhardness measurements). The state diagram of the system was constructed. It was found that the Sb2Se3-Ho2Se3 section is a quasi-binary section of the Ho-Sb-Se ternary system. In the system, the compound HoSbSe3 forms, which melts incongruently at 1050 K and crystallizes in the rhombic system at the unit cell parameters a = 11.855 Å, b = 11.316 Å, c = 4.139 Å, and Z = 4 in the space group Pbnm-D2h16. The solubility of solid solutions based on Sb2Se3 at room temperature reaches 8 mol % Ho2Se3, whereas solid solutions based on Ho2Se3 were not detected.

Interactions and glass formation in the TlAs2Se4-Tl3As2Se3Te3 system

The TlAs2Se4-Tl3As2Se3Te3 system was studied using differential thermal analysis (DTA), powder X-ray diffraction, microstructure observation, and microhardness and density measurements. A phase diagram of the title system was constructed. This system is a quasi-binary join of the TlSe-As2Se3-As2Te3 quasi-ternary system. All alloys of the system under standard conditions are prepared in the glassy form. The system has a eutectic, which contains 50 mol % Tl3As2Se3Te3 and melts at 150°C. The TlAs2Se4-base solid solution in the system extends to 12 mol % Tl3As2Se3Te3, and Tl3As2Se3Te3-based solid solution extends to 20 mol % TlAs2Se4.

A physicochemical study of the Sb2Se3?Nd2Se3 system

We have studied phase relations in the Sb2Se3–Nd2Se3 system and mapped out its T–x phase diagram using differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements. The system contains one compound, with the composition NdSbSe3, which melts incongruently at 865 K and crystallizes in orthorhombic symmetry with the following lattice parameters: а = 12.77(1) Å, b = 14.08(1) Å, and c = 5.82(5) Å (Z = 8, ρmeas = 6.20 g/cm3, ρx = 6.38 g/cm3). At room temperature, the Nd2Se3 solubility in Sb2Se3 is 5 mol % and the Sb2Se3 solubility in Nd2Se3 is 2.5 mol %. The Sb2Se3–Nd2Se3 system has a eutectic located at 15 mol % Nd2Se3, with a melting point at 755 K. The electrical conductivity and thermoelectric power of the (Sb2Se3)1–x(Nd2Se3)x solid solutions have been measured as functions of temperature.

Phase equilibria in the InS-Sb2Te3 system

The interaction character of the InS-Sb2Te3 system was studied by differential thermal analysis, X-ray powder diffraction, microstructure examinations, microhardness measurements, and density determinations, and its phase diagram was constructed. The InS-Sb2Te3 phase diagram is a partially non-quasi-binary section of the In,Sb∥S,Te ternary reciprocal system. Two compounds are formed in the InS-Sb2Te3 system, namely: In3Sb2S3Te3 and InSb2Te3S. Sb2Te3-based solid solutions at room temperature have an extent of up to 6 mol % InS, while InS-based solid solutions are virtually nonexistent.

Phase equilibria in the PbSe-Bi2Se3-Se system and thermodynamic properties of intermediate phases

The Pb-Bi-Se system in the PbSe-Bi2Se3-Se-Se composition region was studied by measurement of concentration circuits of the type (−) PbSe(solid) liquid electrolyte, Pb2+(Pb-Bi-Se)(solid) (+) in the temperature range 300–430 K and by X-ray powder diffraction. A solid-phase equilibrium diagram was constructed, and the formation was confirmed for the ternary compounds Pb5Bi6Se14, Pb5Bi12Se23, and Pb5Bi18Se32, which belong to the homologous series [(PbSe)5]m · [(Bi2Se3)3]n. From the emf versus temperature equations, the partial thermodynamic functions

Liquidus surface projection for the Er-Sn-Se ternary system

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