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 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 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 water-pyridine-butyric acid systems at 25.0°C

The solubility of the components of the ternary water-pyridine-butyric acid system is studied by means of isothermal titration at 25.0°C under normal pressure. Nine nodes are plotted over the area of delayering using the Mertslin section method, and the compositions of the equilibrium liquid phases are determined graphically. It was found that there is a closed binodal curve with two critical points on the solubility diagram of the system; the distribution curve of pyridine between the equilibrium liquid phases demonstrates its preferential distribution into the organic phase.     

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 in the fluorosilicic acid-o-phenylenediamine-water system at 25°C: The crystal structure of o-phenylenediammonium hexafluorosilicate

The interactions in the H₂SiF₆-o-phenylenediamine-H₂O (FSA-PDA-H₂O) system at 25°C is studied using the isothermal solubility method. The solid phases existing in the system are o-PDA (0-23.70 wt % H₂SiF₆) and hexafluorosilicate formulated as (o-PDAH₂)SiF₆ (23.70–44.60 wt % H₂SiF₆). The structure for the latter is solved in single-crystal X-ray diffraction experiments. In the ionic structure of the complex, o-PDAH ₂ ²⁺ cations and SiF ₆ ² anions are linked through H-bonds NH-F((N-F 2.865(2)-2.967(2) Å) into a two-dimensional net. The Si-F bond lengths are 1.6709(12)-1.6958(12) Å.     

Phase diagram of an iodine-potassium iodide-water-ethanol system at 25°C

Phase equilibriums are studied in the isothermal-isobaric sections of the phase diagram of a fourcomponent iodine-potassium iodide-water-ethanol system at 25°C and atmospheric pressure. The compositions of the solvent at which it exhibits the greatest ability to dissolve iodine are established. It is shown that in all the investigated sections, there is three-phase eutonic equilibrium with potassium iodide and crystalline iodine as the solid phases. It is revealed that in the sections containing 30 and 50% of ethanol, potassium iodide serves as the salting in agent for crystalline iodine, due to the formation of polyiodide complexes of various composition in the studied system.     

Solid-liquid phase equilibria in the fullerenol-d-CuCl2-H2O system at 25°C

Solubility in the ternary fullerenol-d-CuCl₂-H₂O system at 25°C is studied by means of isothermal saturation in ampoules. It is established that the diagram consists of two branches corresponding to the crystallization of fullerenol-d crystallohydrate and copper(II) chloride dihydrate and contains a single non-variant eutonic point corresponding to the reciprocal saturation with both solid phases. The salting-in effect on the crystallization branch of CuCl₂ · 2H₂O and the salting-out effect on the crystallization branch of fullerenol-d is revealed.     

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.     

Copper nitrate-formamide-water system at 25°C

The solubility and solid phases in the Cu(NO₃)₂-HCONH₂-H₂O system at 25°C were studied. The formation region of the congruently soluble compound Cu(NO₃)₂ · 2HCONH₂ · 2H₂O was determined. Thysicochemical properties of this complex were investigated by X-ray powder diffraction, differential thermal, crystal-optical, and IR spectroscopic analyses.     

Solubility equilibria in the system Cd(II)-2-mercaptopropionic acid at 25°C

The solubility equilibria between Cd(II) and 2-mercaptoproprionic acid in 3.0 M NaClO₄ at 25°C have been studied by e.m.f. The e.m.f. measurement with both glass and Cd(Hg) electrodes in the range 2.5 < pH < 4.8 were made in solutions where a solid phase coexists with soluble complexes Cd_qA_p. Free ligand and metal ion concentrations were calculated in order to determine the solubility product of CdA (eqn 5). From the values of the formation constants for the soluble complexes and the solubility product, the solubility constants k_spq have been computed. A general equation for the redissolution of the precipitate is proposed and a set of equilibrium constants is given.     

Interaction in the manganese sulfate-carbamide-sulfuric acid-water system at 25°C

Heterogeneous equilibria in the manganese-carbamide-sulfuric acid-water quaternary system at 25°C are studied using the solubility method. The concentration boundaries are determined for crystallization of the initial solid components, eutectic compositions of the ternary systems, and binary compounds formed in the carbamide-sulfuric acid-water and carbamide-manganese sulfate-water systems, as well as for new compounds simultaneously containing carbamide, manganese sulfate, and sulfuric acid at a 1: 4: 1 and 1: 2: 1 ratios.     

Interactions in the zinc bromide-carbamide-hydrobromic acid-water system at 25°C

Interactions in the ZnBr₂-CO(NH₂)₂-HBr-H₂O quaternary system at 25°C were studied using the solubility method. The crystallization regions of the initial eutonic compositions, constituent ternary systems, binary compounds of carbamide with zinc bromide and hydrobromic acid, and two new coordination compounds ZnBr₂ · 4CO(NH₂)₂ · HBr and ZnBr₂ · 2CO(NH₂)₂ · HBr were identified.     

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 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 in the Ag–In–Pd System at 700°C

Summary. Phase equilibria in the Ag–In–Pd system were determined at 700°C based on experimental results for 21 alloys. A ternary compound T₁ (with the approximate composition AgInPd₂) was identified by XRD analysis. These data were compared with the results of a CALPHAD-type prediction, based on binary thermodynamic data only and a symmetrical Redlich–Kister–Muggianu model. The experimental results will serve as a basis for refined thermodynamic modeling of the different phases in this ternary system.