Phase equilibria in the Tl-TlBr-Te system and thermodynamic properties of the compound Tl5Te2Br

The Tl-TlBr-Te composition region of the Tl-Te-Br phase diagram has been explored by DTA, X-ray diffraction, microhardness measurements, and electromotive force (emf) measurements relative to a thallium electrode in concentrations cells. The phase diagrams along a number of joins, the isothermal section at 400 K of the phase diagram, and a projection of the liquidus surface have been constructed. Extensive phase-separation areas, including a three-liquid-phase field in the Tl-TlBr-Tl₂Te subsystem, have been revealed. The homogeneity ranges and primary crystallization fields of phases have been mapped, and the coordinates of nonvariant and univariant equilibria in the T-x-y diagram have been determined. The standard thermodynamic functions of formation of the Tl₅Te₂Br compound and its standard entropy have been derived from emf data.     

The phase diagram of CsNO<Subscript>3</Subscript>–RbNO<Subscript>3</Subscript>

The phase transitions of RbNO₃ and the binary phase diagram of (Cs,Rb)NO₃ were investigated at atmospheric pressure, using simultaneous direct and differential thermal analysis, μDTA and DSC techniques. A fourth phase transition of RbNO₃ has been observed at temperature near the melting point. The phase diagram of this system is characterised by a eutectic, two eutectoid and an azeotropic-like invariants. Three limited solid solutions and two continuous solid solutions have been detected at low temperature.     

Four-component system LiF-K2WO4-CaF2-CaWO4

The four-component system LiF-K₂WO₄-CaF₂-CaWO₄ has been studied by physicochemical analysis. The phase and crystallization trees have been predicted a priori and have been experimentally verified by constructing a topological model of the phase diagram and by solving the equations expressing the general law of liquidus surface formation. The heat-storage properties of the eutectic compositions are evaluated.     

Four-component system LiF-K<Subscript>2</Subscript>WO<Subscript>4</Subscript>-CaF<Subscript>2</Subscript>-BaWO<Subscript>4</Subscript>

The four-component system LiF-K₂WO₄-CaF₂-BaWO₄ has been studied for the first time using physicochemical methods. The a priori prediction of the phase complex revealed the phase tree and crystallization path of the system. The prediction was verified experimentally, by construction of a topologic model of the phase diagram, and the solution of the equations of the general law of liquidus-surface formation. The density has been measured, and the heat-storage properties of eutectic mixtures have been estimated.     

The phase diagram of the AgNO3−KNO3 system determined by differential scanning calorimetry

The phase diagram for the AgNO₃?KNO₃ system has been determined using differential scanning calorimetry (DSC). Eutectic point has been found at 391 K andX _Ag=0.580 mole fraction AgNO₃. The DSC curves indicate the existence of an intermermediate compound (AgNO₃·KNO₃) in the KNO₃-rich region of the phase diagram. This compound was identified in the solid phase by X-ray diffraction. The melting and the crystallization processes were followed with the aid of a hot stage microscope, too.     

Phase relations in the ZrO2-FeO system

We present the results of the investigation of the ZrO₂-FeO system under an inert atmosphere. We have refined the position of the eutectic point, which lies at 1332 ± 5°C and 10.3 ± 0.6 mol % ZrO₂. The iron oxide solubility boundaries in zirconium dioxide have been determined over a wide temperature range taking into account the polymorphism in ZrO₂. A phase diagram for the system has been designed.     

Molecular dynamics simulation of the phase behavior of AgI<Subscript>1-x</Subscript>Cl<Subscript>x</Subscript>

Summary The temperature and pressure dependencies of the structure and transport properties of AgI_1-xCl_x are studied by means of molecular dynamics. From the results of the calculations, the P-T phase diagram for the AgI_0.8Cl_0.2 system has been obtained. The phase diagram indicates that the superionic phase transition temperature increase with the application of pressure. It is also pointed out that AgI_1-xCl_x has a tendency of phase separation.     

Phase equilibria in the Na,Ca||SO4,CO3,F-H2O system at 25°C

Phase equilibria in the Na,Ca|SO₄,CO₃,F-H₂O system at 25°C have been studied using the translation method. The existence of seven invariant points, 21 monovariant curves, and 22 divariant fields has been established. These data were used to construct a looped phase diagram (phase complex) for the title system at 25°C.     

Correction to the phase equilibria in the FeMnTiO system

The reported phase relations for the FeMnTiO system (R. R. Merritt, J. Solid State Chem., 43, 267, 1982) have been redetermined because they were found to be affected by the presence of 1.34 wt% Al₂O₃ in the TiO₂ used. This impurity lowers the temperature at which the pseudobrookite phase is stable. The results of the new work reaffirm the changes to the phase diagram that result from the replacement by manganese of part of the iron in the FeTiO system. On the basis of the earlier results, a phase diagram is proposed for an aluminum-containing five-component system.     

Phase Relations in Metastable Equilibria of the PbO-GeO2 System

Metastable phase relations in the PbO-GeO₂ system have been studied by DTA and X-ray powder diffraction. Metastable equilibrium was acquired during the solidification of a melt while it was slowly (at 8 K/min) cooled from temperatures slightly exceeding the critical value for a given composition. In the metastable equilibrium acquired in this way, α-PbO-base solid solution and four metastable individual phases were observed in the system at room temperature, with different structures and different thermal stabilities. A metastable equilibrium phase diagram has been mapped.     

Subsolidus area of the AlVO4−Al2(MoO4)3 system

The behaviour of Al₂(MoO₄)₃ towards AIVO₄ in the subsolidus area, over the whole component concentration range, has been studied using the DTA and XRD methods. The experimental results have been presented in the form of a phase diagram. It has been found that components of the system of interest do not remain in equilibrium, and AlVO₄?Al₂(MoO₄)₃ system is not a real two-component system, even in the subsolidus area.     

Phase Relations in the CoMoO4-CoV2O6-CoO System Quasi-Binary Line Co3V2O8-CoMoO4

The phase relationship in the pseudobinary Co₃V₂O₈-CoMoO₄ system have been determined by differential thermal analysis (DTA) and X-ray diffraction (XRD). A new compound Co_2.5 VMoO₈, stable up to 1080±5°C has been found in the system. The results obtained are presented in the form of a phase diagram. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phases in the subsolidus area of the system CuO–V2O5–Fe2O3

The phase equilibria in the solid state in the system FeVO₄?CCu₃V₂O₈ and FeVO₄?CCuO have been determined. Based on the obtained DTA and XRD analysis results and some additional research, a phase diagram in the whole subsolidus area of the system CuO?CV₂O₅?CFe₂O₃ has been worked out. Eighteen subsidiary subsystems can be distinguished in this ternary system. Basic properties of the obtained phases with howardevansite- and lyonsite-type structure have been investigated by DTA, IR, and SEM methods.     

Phase equilibria in the Na,K‖CO3,HCO3,F-H2O system at 50°C

Phase equilibria in the Na,K??CO₃,HCO₃,F-H₂O system at 50°C have been determined using the translation method. The system is found to be characterized by the existence of 21 divariant double-saturation fields, 19 monovariant triple-saturation curves, and six invariant quadruple-saturation points. A looped phase diagram (phase complex) for the title system at 50°C has been constructed.     

Phase equilibria in the Tl-TlBr-S system

The polythermal sections TlBr-Tl₂S, TlBr-Tl₄S₃, TlBr-TlS, and Tl₆SBr₄-Tl; the isothermal section at 300 K of the phase diagram; and the projection of the liquidus surface of the Tl-S-Br system have been investigated in the composition region Tl-TlBr-S by DTA, X-ray powder diffraction analysis, and microhardness measurements. The primary crystallization regions, including that of the only ternary compound (Tl₆SBr₄), have been determined, and the types and coordinates of the invariant and univariant equilibria in the phase diagram are determined.     

Physicochemical Interaction in the TlInSe<Subscript>2</Subscript>–TlInP<Subscript>2</Subscript>Se<Subscript>6</Subscript> System

Phase equilibria in the TlInSe₂–TlInP₂Se₆ system have been studied for the first time by classic physicochemical analysis methods (differential thermal analysis (DTA), X-ray diffraction, and microstructural analysis (MSA)), and its phase diagram has been plotted. The system belongs to the eutectic type (Rooseboom V type) and forms boundary solid solutions based on the initial complex selenides.     

Revised Phase Diagram of the System NaF–NaBF4

Summary. The phase diagram of the binary system NaF–NaBF₄ was determined using the thermal analysis method. Subsequent coupled analysis of the thermodynamic and phase diagram data was carried out to calculate the thermodynamically consistent phase diagram. The system NaF–NaBF₄ forms a simple eutectic phase diagram with the calculated coordinates of the eutectic point: 8.1 mol% NaF, 91.9 mol% NaBF₄, and 385.7°C. The probable inaccuracy in the calculated binary phase diagram is 9°C.     

Thermodynamic study of sodium-iron oxides: Part II. Ternary phase diagram of the Na-Fe-O system

Studies on ternary phase diagrams of the Na-Fe-O system have been carried out from the thermodynamic point of view. Thermodynamic data of main ternary Na-Fe oxides Na₄FeO₃(s), Na₃FeO₃(s), Na₅FeO₄(s) and Na₈Fe₂O₇(s) have been assessed. A user database has been created by reviewing literature data together with recent DSC and vapor pressure measurements by the present authors. New ternary phase diagrams of the Na-Fe-O system have been constructed from room temperature to 1000 K. Stable conditions of the ternary oxides at 800 K were presented in predominance diagram as functions of oxygen pressure and sodium pressure.     

Selected X-ray diffraction and differential scanning calorimetry measurements on nonaqueous liquid crystals and gel phases in the K-myristinate/glycerol binary system

Samples from the three selected concentrations x _KC14 = 0.25,0.37, and 0.50 of the K-myristinate/glycerol (KC₁₄/Gl) binary system have been investigated by means of small- and wide-angle X-ray diffraction measurements as well as differential scanning calorimetry (DSC) measurements as a function of temperature. The results are – The G₁ gel phase, contained in the preliminary phase diagram according to Dörfler and Senst [(1993) Colloid Polym Sci 271: 173], is nonexistent. – The same applies of the isotropic phase in the preliminary phase diagram according to Dörfler and Senst. Initially an isotropic or a cubic phase was assumed based on polarized microscopy texture observations. X-ray diffraction and DSC measurements provided no indication for their existence. – Due to the nonexistence of the G₁ and isotropic phases the preliminary phase diagram of the KC₁₄/Gl binary system had to be corrected. The region of the lamellar phase extends over a wider region. – X-ray diffraction and DSC measurements provided concordant results, which were further confirmed by electron microscopic investigation. Differences in phase-transition points from DSC data obtained for rising and falling temperatures have been observed. – The crystalline-to-gel phase transition correlates with a sharp shift in the d value of the first small-angle reflex. – The gel phase is accompanied by a distinct splitting of the first small-angle reflexes. The wide-angle reflexes show rearrangement and reduced intensity. – Similar to the crystalline-to-gel phase transition, the gel-to-lamellar phase transition is accompanied by a sharp change in the d values.