Phase diagram of the In3As2Se6-In3As2S3Se3 system

The In₃As₂Se₆-In₃As₂S₃Se₃ system has been investigated by methods of physicochemical analysis (DTA, X-ray powder diffraction, MSA) and by microhardness and density measurements. The phase diagram of the system, which is the quasi-binary section of the As-In-S-Se quaternary system, has been constructed. The region of the In₃As₂Se₆-based solid solutions is extended to 7 mol %, and the In ₃As₂S₃Se₃-based region to 15 mol %. A new quaternary compound In₆As₄S₃Se₉ is found in the system. Original Russian Text ? I.I. Aliev, R.S. Magammedragimova, A.A. Farzaliev, Dzh. Veliev, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 4, pp. 691–694.     

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.     

Heats of immersion of amorphous As2S3, As2S5 and As2Se3 in organic liquids

The heats of immersion of hydrophobic, amorphous arsenic chalcogenides have been measured in several organic liquids. For hexane, butanol, butylchloride and nitropropane, the heats of immersion with As₂S₃, As₂S₅ and As₂Se₃ showed linear dependences on the dipole moment of the wetting liquid molecule. From the results the average values of the electrostatic field strength were calculated to be 0.29 × 10⁵, 0.31 × 10⁵, and 0.57 × 10⁵ e.s.u. cm^?2. The heats of immersional wetting of As₂S₃ and As₂Se₃ in n-alkanols linearly increased with an increase of n, the number of carbon atoms in C_nH_2n+1OH. The contributions due to polarization of the liquid molecule by the electrostatic field of the solid surface, due to the dispersion force and due to the interaction between the dipole moment of the liquid with the electrostatic field of the solid were calculated by applying the additivity of intermolecular forces. The result showed that the dispersion force was the dominant contribution to the interaction in As chalcogenides-n-alkanol systems.     

Compounds in the system Cu2SeAs2Se3

The phase diagram Cu₂SeAs₂Se₃ was investigated by thermal and X-ray methods. Cu₂Se has a limited solubility for As₂Se₃ (5 mole% at 769 K). The stoichiometric compound Cu₃AsSe₃ exists between 696 and 769 K. Cu₄As₂Se₅, a phase at 66.6 mole% Cu₂Se, decomposes peritectically at 746 K. The narrow homogeneity range (4 mole% at 683 K) extends far into the ternary space. CuAsSe₂ also decomposes peritectically at 683 K. A degenerated eutectic between CuAsSe₂ and As₂Se₃ was found at 641 K. Single crystals of Cu₄As₂Se₅ were grown in a salt melt. A metastable modification of the high-temperature phase Cu₃AsSe₃ can be obtained by quenching. Cu₄As₂Se₅ (space group R3, lattice constants a = 1404.0(1) pm, c = 960.2(1) pm), Cu₆As₄Se₉, obtained by Cambi and Elli, and Cu₇As₆Se₁₃ of Takeuchi and Horiuchi are different versions of a sphalerite-type compound with a broad homogeneity range in the system CuAsSe. CuAsSe₂ is possibly monoclinic with lattice parameters of a = 946.5(1) pm, b = 1229.3(1) pm, c = 511.7(1) pm, and β = 98.546(4)°. The enthalpy of mixing of Cu₂Se and As₂Se₃ in the liquid state is endothermic.     

Character of interaction and glass formation in the TlAs<Subscript>2</Subscript>Se<Subscript>4</Subscript>-Tl<Subscript>3</Subscript>As<Subscript>2</Subscript>S<Subscript>3</Subscript>Se<Subscript>3</Subscript> system

The TlAs₂Se₄-Tl₃As₂S₃Se₃ system was investigated by physicochemical methods (DTA, X-ray powder diffraction, microstructural analysis), and its phase diagram was constructed. The TlAs₂Se₄-Tl₃As₂S₃Se₃ join is a quasi-binary internal section of the As-Tl-S-Se quaternary system. The solubility range of TlAs₂Se₄-based solid solutions is extended to 7 mol %, and the region of Tl₃As₂S₃Se₃-based solid solutions is extended to 15 mol %.     

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.     

Phase diagram of the Pb5Sb4S11-Pb2SnSb2S6 system

The Pb₅Sb₄S₁₁-Pb₂SnSb₂S₆ system was studied by a number of physicochemical methods, and its phase diagram was constructed. It was found that the system under investigation is a quasi-binary eutectic type section of the SnS-PbS-Sb₂S₃ ternary system. The coordinates of the eutectic are found to be 33 mol % Pb₅Sb₄S₁₁ and 750 K. Regions of solid solutions based on Pb₅Sb₄S₁₁ (6 mol % Pb₂SnSb₂S₆) and Pb₂SnSb₂S₆ (4 mol % Pb₅Sb₄S₁₁) were determined.     

Phase equilibrium in the Pb2SnSb2S6-SnS system

The Pb₂SnSb₂S₆-SnS system was studied over a wide range of concentrations using a set of physicochemical methods (powder X-ray diffraction, DTA, microstructure examination, and microhardness measurement). A phase diagram for the title quasi-binary join was constructed for the first time. The phase diagram is of the eutectic type; the eutectic coordinates are 25 mol % SnS and 775 K. The extents of solid solutions based on the terminal components were determined to be 10 mol % SnS and 5 mol % Pb₂SnSb₂S₆. Alloys having compositions in the SnS-based solid solution region are semiconductors.     

Interaction in the Ga2S3-Y2O2S system

The phase diagram of the Ga₂S₃-Y₂O₂S system has been investigated by differential thermal, X-ray powder diffraction, microstructural, and thermodynamic analyses. It has been established that the system is eutectic, and solubility at 295 K from the Ga₂S₃ side reaches 3 mol % Y₂O₂S. The coordinates of the eutectic point are 14 mol % Y₂O₂S and 1320 K.     

Tl2S-Sb2S3-Bi2S3 quasi-ternary system

The Tl₂S-Sb₂S₃-Bi₂S₃ quasi-ternary system (system A) was studied using DTA, X- ray powder diffraction, microstructure examination, and microhardness measurements. TlSbS₂-Tl₄Bi₂S₅(TlBiS₂, Bi₂S₃), Sb₂S₃-TlBiS₂, Tl₃SbS₃-TlBiS₂(Bi₂S₃), and [TlSb_0.5Bi_0.5S₂]-Tl₂S isopleths; isothermal sections at 500 K; and liquidus surface projection of system A were constructed. Characteristic features of the title system are extensive fields of solid solutions extended along the TlSbS₂-TlBiS₂ quasi-binary section and a continuous solubility belt 1–2 mol % wide extended along the Sb₂S₃-Bi₂S₃ binary subsystem. Primary separation fields of phases and the types and coordinates of invariant and monovariant equilibria in system A were determined.     

Interactions of Cr2S3 with GeS2 and Cu2GeS3

The interactions in the GeS₂-Cr₂S₃ and Cu₂GeS₃-Cr₂S₃ sections were studied by differential thermal analysis and X-ray powder diffraction. The GeS₂-Cr₂S₃ section was shown to be quasi-binary, with a degenerate eutectic; no ternary compound was formed. In the Cu₂GeS₃-Cr₂S₃ section, a quaternary phase of variable composition having a homogeneity range of 69–75 mol % Cr₂S₃ crystallized in the cubic system. The samples of this composition are spin glasses with freezing temperatures of 20–25 K.     

Konzentrationen von Isomeren des Typs P m As4−m X 3 in P4S3-As4S3- und P4Se3-As4Se3-Mischungen

The reactions of P₄S₃ with As₄S₃ and of P₄Se₃ with As₄Se₃ in the molten state yields molecules of the type P _m As_4–m S₃ and P _m As_4–m Se₃, respectively. A method was developed to separate the different components by the HPLC technique, and to determine their concentrations. The identification of the isomers in the HPLC pattern was achieved with the aid of the LC-MS method. In the selenium system, the distribution of the different species is statistical. In the system P₄S₃-As₄S₃, the formation of PAs₃S₃ with one phosphorus atom in the apical position is favoured.

     

Solid-phase equilibria and thermodynamic properties of the Tl2Se-As2Se3-Se system

The Tl₂Se-As₂Se₃-Se system in the equilibrium crystalline state was studied by differential thermal analysis, X-ray powder diffraction, and measurements of emf relative to a thallium electrode within the temperature range 300–400 K. An isothermal section of the phase diagram at 300 K was constructed. The formation of ternary compounds Tl₃AsSe₄, TlAsSe₂, and Tl₃AsSe₃ was confirmed, and the locations of their phase regions were determined. From the emf measurement data, the partial molar functions of thallium in alloys, the standard thermodynamic functions of formation, and the standard entropies of the above ternary compounds were calculated.     

Magnetic susceptibility and torque measurements of FeV2S4, FeV2Se4 and FeTi2Se4

Magnetic susceptibility and torque measurements of FeV₂S₄, FeV₂Se₄ and FeTi₂Se₄ were made using the powder and the single crystal samples. The inverse susceptibility of FeV₂S₄, FeV₂Se₄ and FeTi₂Se₄ changed its slope at 850, 820 and 700 K, respectively, at which temperature the order-disorder transition of cation vacancies should seem to take place. Above these temperatures the paramagnetic moment obtained for these compounds was in the range of 5.26–5.37 μ_B, close to that of the high spin state Fe²⁺. Below these temperatures the paramagnetic moment was reduced to 4.23–4.35 μ_B.The antiferromagnetic spin axis of FeV₂S₄ was in the neighborhood of the [101] direction and that of FeV₂Se₄ and FeTi₂Se₄ in the direction of the c-axis. The large magnetic anisotropy observed and the preference of the magnetic moments for the direction of the c-axis were attributed to the spin-orbit interaction of Fe²⁺ electrons in the trigonal crystal field.     

Phase equilibrium in the PbSnS2-PbSb2S4 system

The PbSnS₂-PbSb₂S₄ system was studied by physicochemical methods, and its phase diagram was plotted. The system is quasi-binary; solid solutions regions based on PbSnS₂ (6 mol % PbSb₂S₄) and PbSb₂S₄ (12 mol % PbSnS₂) were revealed. At a component ratio of 1: 1, a congruently melting compound Pb₂SnSb₂S₆ is formed. Pb₂SnSb₂S₆ single crystals were obtained by chemical transport. The unit cell parameters of Pb₂SnSb₂S₆, which crystallizes in orthorhombic system, were determined: a = 15.22 ?, b = 10.68 ?, c = 3.90 ?.     

Interaction in the TlSe-Pr2Se3 system

The interaction of components in the TlSe-Pr₂Se₃ system was studied by differential thermal, X-ray powder diffraction, and microstructural analyses and also by microhardness and density measurements. The state diagram of this system was constructed. It was found that the section TlSe-Pr₂Se₃ is a quasi-binary section of the Tl-Pr-Se ternary system. In the TlSe-Pr₂Se₃ system at the component ratio 1: 1, a new chemical compound, TlPr₂Se₄, forms, which melts congruently at 1295°C. In the system based on TlSe, solid solutions form until 3.5 mol % Pr₂Se₃, and in the system based on Pr₂Se₃, solid solutions occur until 2.5 mol % TlSe.     

Phase diagrams of sections in the EuS-Cu2S-Nd2S3 system

Phase equilibria in the EuS-Cu₂S-Nd₂S₃ system were studied in an isothermal (970 K) section and NdCuS₂-EuS and Cu₂S-EuNdCuS₃ polythermal sections. The complex sulfide EuNdCuS₃ has an orthorhombic crystal lattice (space group Pnma; a = 1.10438(2) nm, b = 0.40660(1) nm, c = 1.14149(4) nm), is isostructural to BaLaCuS₃, and melts incongruently at 1470 K: EuNdCuS₃ (0.50 EuS; 0.50 NdCuS₂) ai 0.18 EuS ss (0.88 EuS; 0.12 NdCuS₂) + 0.82 L (0.415 EuS; 0.585 NdCuS₂); ΔH = 17.8 kJ/mol. Within the range 0.5 mol % EuS, EuNdCuS₃-based solid solutions were not found. At 970 K, the tie lines pass from the compound EuNdCuS₃ to Cu₂S, EuS, NdCuS₂, and EuNd₂S₄ phases and lie between the NdCuS₂ phase and solid solutions (ss) of γ-Nd₂S₃ with EuNd₂S₄. Eutectics are formed between the compounds NdCuS₂ and EuNdCuS₃ at 32.0 mol % EuS T = 1318 K and between the compounds Cu₂S and EuNdCuS₃ at 20.5 mol % EuNdCuS₃ and T = 1142 K. Five main subordinate triangles were identified in the system.     

Neue Moleküle A4B3 im System P4Se3–As4Se3

Novel A₄B₃ Molecules in the System P₄Se₃–As₄Se₃ By means of ³¹P-NMR and masspectroscopic measurements in the system P₄Se₃–As₄Se₃ was shown that in the melt and vapour phase at all compositions molecules of the type P_{4 ? n}As_nSe₃ are formed. A separation was possible by liquid chromatography (RP 18-column). The concentration distribution of the different species is nearly statistical. In the solid state at ambient temperature regions of solid solubility with α-P₄Se₃, α⁺-phase, α-P₄S₃ and α-As₄Se₃ structure were observed. P₃AsSe₃ could be transformed into a plastically-crystalline phase with β-P₄S₃ structure. At higher temperatures the phase decomposes slowly. The thermal behaviour of PAs₃Se₃ is strongly influenced by the heating rate. Using low heating rates it decomposes into an amorphous phase, by fast heating a transformation into a metastable plastically-crystalline modification was achieved. During long extraction with CS₂ molecules P_{4 ? n}As_nS_{3 ? m}Se_m are formed by an exchange reaction. They can also be prepared by melting the proper amounts of the elements.     

The preparation and properties of BaTa0.8S3, BaNb0.8S3, and BaTa0.8Se3

Compounds of the formulas BaTa_0.8S₃, BaNb_0.8S₃, and BaTa_0.8Se₃ were prepared by two methods: reaction of the elements in evacuated silica tubes and reaction of H₂S over mixtures of BaCO₃ and 0.4Ta(Nb)₂O₅. They have the hexagonal BaNiO₃-type structure and are diamagnetic semiconductors. From the stoichiometries and properties we conclude that Nb and Ta are pentavalent.     

Ag2Se-Tl2Se-Bi2Se3 quasi-ternary system

The Ag₂Se-Tl₂Se-Bi₂Se₃ quasi-ternary system (system A) was studied using DTA, X-ray powder diffraction, microstructure examination, and microhardness measurements. TlBiSe₂-AgBiSe₂, AgTlSe-AgBiSe₂, AgTlSe-Bi₂Se₃, and Tl₂Se-AgBiSe₂ polytherms, isothermal sections at 500 and 800 K, and liquidus surface projection of system A were constructed. System A is congruently triangulated into the following subordinate triangles: Tl₂Se-AgTlSe-Tl₉BiSe₆ (I), AgTlSe-Tl₉BiSe₆-TlBiSe₂ (II), Ag₂Se-AgTlSe-TlBiSe₂ (III), Ag₂Se-AgBiSe₂-TlBiSe₂ (IV), and AgBiSe₂-TlBiSe₂-Bi₂Se₃ (V). Subsystems I, III, and V are ternary systems with three-phase eutectic equilibrium; system II has a three-phase eutectic, and system IV is characterized by several invariant and monovariant peritectic and eutectic equilibria. Primary crystallization and homogeneity fields were outlined, and the types and coordinates of invariant and monovariant equilibria in system A were determined. A characteristic feature of the title system is an extensive field of solid solutions between high-temperature cubic AgBiSe₂ and TlBiSe₂ phases; this field lies as a continuous belt along the AgBiSe₂-TlBiSe₂ quasibinary section and covers about one-fourth of the surface area of the triangular diagram of system A.