Phase equilibria in the Ag–Au–In system at 500°C

Phase equilibria in Ag–Au–In system at 500°C are investigated by means of electron microscopy, electron probe microanalysis, and X-ray powder diffraction. The part of the system’s isothermal cross section with an indium content of up to 50 at % is constructed.     

Phase equilibria in the aluminium-rich side of the Al–Zr system

The Al-rich phase equilibria in the Al–Zr binary system were investigated experimentally. The phase diagram for compositions up to 40 at.% Zr was determined experimentally by differential thermal analysis and metallography. Three stable intermetallic compounds exist in this region of the diagram: Al₃Zr₂, Al₂Zr, and Al₃Zr. The peritectic melting of Al₃Zr₂ and the congruent melting of Al₂Zr were confirmed. Al₃Zr, the most Al-rich intermetallic compound, melts peritectically, which contradicts information available in the literature. In addition, the reaction between Al₃Zr and the (Al) solid solution seems to be of eutectic nature, in contradiction with previous results found in the literature. Based on these new experimental evidence, a revised phase diagram is drawn.     

Phase diagram of the Sn–P system

Journal of Thermal Analysis and Calorimetry - The T–x diagram of the Sn–P system was studied by differential thermal analysis, X-ray phase analysis and local X-ray spectral...     

Phase equilibria in the ternary system NaF–KF–CsF

The ternary eutectic system CsF–KF–NaF was studied by differential thermal analysis. The melting point and composition of the ternary eutectic were determined, and so was the boundary of the region of limited series of solid solutions within the composition triangle. The compositions of crystallizing phases were confirmed by X-ray powder diffraction analysis. The specific enthalpy of melting of the ternary eutectic was experimentally found.     

Phase equilibria in the Sn–As–Ge and Sn–As–P systems

T–x diagrams of polythermal GeAs–SnAs, GeAs–Sn₄As₃ sections of the Sn–As–Ge system and Sn₄P₃–Sn₄As₃ section of the Sn–As–P system were constructed using the results of X-ray powder diffraction and differential thermal analyses. It was found that the section GeAs–Sn₄As₃ is not quasi-binary due to realization of four-phase peritectic transformation L + SnAs ? GeAs + Sn₄As₃ at the temperature of 834 K. The quasi-binary section GeAs–SnAs represents a phase diagram of the eutectic type with the following coordinates of eutectic reaction: temperature of the eutectic point is 840 K, and composition is 20 mol% GeAs. In the Sn–As–P system, the existence of the solid-solution range indicated as (Sn₄As₃) _x (Sn₄P₃)_1?x  was defined. The polythermal section Sn₄P₃–Sn₄As₃ is not quasi-binary due to the fact that in the composition range with a high content of tin arsenide discussed section intersects the peritectic part of the three-phase volume (L + SnAs + α) of the ternary diagram.     

Phase equilibria in a polyethylene–polystyrene system

The method of optical interferometry is used to study the interaction of PE with PS in situ. On the basis of the obtained data, phase diagrams of the PE–PS system are constructed for a number of molecular masses of the components. For PE and PS oligomers, the UCMT values are determined. Pair parameters for the interaction of homopolymers are calculated, and their dependences on temperature and molecular mass are considered. The quantitative analysis of the behavior of high-molecular-mass fractions of PE and PS at high temperatures is carried out, and the regions of a partial compatibility of the components are predicted.     

Phase equilibria in binary subsystems of urea–biuret–water system

Joint results of the differential scanning calorimetry (DSC) and thermogravimetry (TG) experiments were the basis for the fusion enthalpy and temperature determination of the biuret (NH₂CO)₂NH (synthesis by-product of the urea fertilizer (NH₂)₂CO). Recommended values are Δ_m H = (26.1 ± 0.5) kJ mol⁻¹, T _m = (473.8 ± 0.4) K. The DSC method allowed for the phase diagrams of “water–biuret,” “water–urea,” “urea–biuret” binary systems to be studied; as a result, liquidus and solidus curves were precisely defined. Stoichiometry and decomposition temperature of the biuret hydrate identified, composition of the compound in “urea–biuret” system was suggested.     

Phase equilibria involving solid solutions in the Li–Mn–O system

Phase equilibria involving LiMn₂O_4-, Li₂MnO_3-, LiMnO_2-, Mn₃O_4-, and MnO-base solid solutions were studied with varied temperature and partial oxygen pressure. The \({P_{{o_2}}}\)–T and x–y projections of the P–T–x–y phase diagram of the Li–Mn?O system were constructed, as well as the key x–y isotherms of the Li₂O–MnO–MnO₂ quasi-ternary system. In some experiments, the authors’ hydride lithiation method was employed to prepare lithium-rich homogeneous three-component nonstoichiometric phases.     

Phase equilibria in the ErPO4–K3PO4 system

The phase equilibria occurring in the ErPO₄–K₃PO₄ system were investigated by the thermal analysis, FTIR, and X-ray powder diffraction methods. On the basis of obtained results, the related phase diagram is proposed. This system includes one intermediate compound, K₃Er(PO₄)₂; the double phosphate melts incongruently at 1355 °C and occurs in two polymorphic forms; transformation β/α-K₃Er(PO₄)₂ proceeds at 420 °C. The eutectic occurs at the composition of 58.5 wt% K₃PO₄, 41.5 wt% ErPO₄ at 1317 °C.     

Phase equilibria in the YPO4–Rb3PO4 system

The phase equilibria occurring in the YPO₄–Rb₃PO₄ system were investigated by thermoanalytical methods, X-ray powder diffraction, and ICP-OES. On the basis of the obtained results, its phase diagram is proposed. It was found that the system includes two intermediate compounds Rb₃Y(PO₄)₂ and Rb₃Y₂(PO₄)₃. The Rb₃Y(PO₄)₂ compound melts congruently at 1300 °C. The Rb₃Y₂(PO₄)₃ orthophosphate was previously unknown. This intermediate compound is high-temperature unstable and decomposes within the temperature range 1300–1330 °C to YPO₄ and Rb₃Y(PO₄)₂. The decomposition process is irreversible. It was found that the Rb₃Y₂(PO₄)₃ orthophosphate is isostructural with Rb₃Yb₂(PO₄)₃ and crystallizes in the cubic system (a = 1.70226 nm).     

Au–Cu Phase Diagram

Phase equilibria have been extrapolated to low temperatures, and a condensed phase diagram has been plotted for the Au–Cu system to be consistent with the third law of thermodynamics.     

Phase equilibria in the Sm–Al–Si system at 500 °C

The isothermal section at 500 °C of the Sm–Al–Si system has been experimentally investigated by using scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. Four intermetallic compounds have been confirmed: τ₁-SmAl₂Si₂ (hP5-CaAl₂Si₂ type), τ₂-SmAl_xSi_1?x (tI12-Th₂Si type), τ₄-SmAl_0.5Si_0.5 (oS8-CrB type) and τ₅-Sm₆Al₃Si (tI80-Tb₆Al₃Si type). A new ternary intermediate has been found: τ₃-Sm₄Al₃Si₃ that crystallizes orthorhombic isostructural with Pr₄Al₃Ge₃.     

Phase equilibria of the Dy–Al–Si system at 500 °C

The isothermal section at 500 °C of the Dy–Al–Si system was studied in the whole concentration range. The alloys were characterized by X-ray powder diffraction, scanning electron microscopy and electron micro-probe analysis. A few samples were analysed by differential thermal analysis. The following intermetallic compounds, some of them showing variable composition, were found: DyAl₂Si₂ (τ₁), hP5-CaAl₂O₂ structure type, Dy₂Al₃Si₂ (τ₂) mS14-Y₂Al₃Si₂ structure type, Dy₂Al_1+x Si_2−x (τ₃), 0 ≤ x ≤ 0.25, oI10-W₂CoB₂ structure type and Dy₆Al₃Si (τ₄), tI80-Tb₆Al₃Si structure type. A number of binary phases dissolve the third element forming ternary solid solutions: Dy(Al_1−x Si _x )₃, 0 ≤ x ≤ 0.5, hP16-Ni₃Ti structure type, Dy(Al _x Si_1−x )₂, 0 ≤ x ≤ 0.1, oI12-GdSi₂ structure type, Dy(Al _x Si_1−x )_1.67, 0 ≤ x ≤ 0.2, oI12-GdSi₂ structure type, DyAl _x Si_1−x , 0 ≤ x ≤ 0.2, oC8-CrB, and Dy₅(Al _x Si_1−x )₃, 0 ≤ x ≤0.3, hP16-Mn₅Si₃ structure type. The melting point of Dy₆Al₃Si was determined.     

Phase equilibria in the Cu–Cu<Subscript>2</Subscript>Se–As system

Phase equilibria in the Cu–Cu₂Se–As were investigated by differential thermal analysis and X-ray powder diffraction analysis. Informative plots describing this system were constructed, viz., the polythermal sections Cu_0.667Se_0.333–As, Cu_0.667Se_0.333–Cu_0.735As_0.265, and Cu_0.8Se_0.2–As, the isothermal section of the phase diagram at 300 K, and the projection of the liquidus surface. The obtained results differ from the published data in length of fields of primary crystallization of phases and in coordinates of a number of invariant equilibrium points.     

Phase equilibria and critical phenomena in the cesium nitrate–water–pyridine ternary system

The solubilities of components, phase equilibria, and critical phenomena in the cesium nitrate–water–pyridine ternary system are studied in the 5–100°C temperature range by the visual–polythermal method. Cesium nitrate is found to exhibit a salting-out effect at temperatures above 79.9°C causing phase separation in homogeneous water–pyridine solutions. The temperature of formation of the critical monotectic tie line (79.9°C) and the compositions of solutions corresponding to the liquid–liquid critical points at three temperatures are determined. The pyridine distribution coefficients between the aqueous and organic phases of the monotectic state at 85.0, 90.0, and 100.0°C are calculated. Their values demonstrate that salting-out of pyridine from aqueous solutions by cesium nitrate increases at higher temperatures. The plotted isotherms of phase diagrams confirm the fragment of the scheme of topological transformation of the phase diagrams of salt–binary solvent ternary systems with salting-in and salting-out phenomena.     

Phase equilibria in the solid state and colour properties of the CuO–In2O3 system

Phase equilibria up to solidus line in CuO?CIn₂O₃ system have been investigated using XRD and DTA/TG methods. According to the results, only one compound of the formula Cu₂In₂O₅ formed in the system studied. Its thermal stability was determined in the air and argon proving that the compound did not melt but underwent decomposition. The decomposition of Cu₂In₂O₅ in the air atmosphere began at 1080?°C, while in argon at 835?°C. Additional studies were undertaken to determine the hitherto unknown colour properties of samples representing the CuO?CIn₂O₃ system in the equilibrium state.