Phase equilibrium diagram of the system MnCrO

A hypothetical oxygen pressure-composition phase diagram and a projection of the oxygen pressure-temperature-composition diagram on the composition triangle were constructed from phase equilibria in the system MnCrO on the basis of the data available in literature. The temperature-composition phase equilibrium diagram of this same system in air was specified. Isomorphism of solid solutions with spinel and hausmannite structure and their intertransformation was studied. Two chemical compounds, MnCr₂O₄ and Cr₄Mn₂₈O₄₈, are supposed to exist in the system.     

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 diagram of the eutectic benzoic acid-naphthalene system in the temperature range of 300–400 K

Liquid-solid phase equilibria are studied in the eutectic benzoic acid-naphthalene system by means of thermic analysis (DTA, CTA), on the basis of which the liquidus line and eutectic point (x _e ≈ 50 mol %, T _e ± 340 K) are determined and the phase diagram is constructed. Average precrystallization supercooling temperatures ΔT _L ^? of the liquid phase relative to liquidus temperature T _L are determined, allowing us to locate the region of solution metastability on the phase diagram. Excessive functions of the components in the liquid phase are found via thermodynamic modeling using the Margules equation and experimental data. The boundaries of the region of liquid solution metastability are estimated from the thermodynamic conditions of solution stability.     

Phase diagram and crystal chemistry of the La–Ca–Co–O system

The phase diagram of the La–Ca–Co–O system at 885 °C in air has been determined. The system consists of two materials that have interesting thermoelectric properties, namely, the misfit layered thermoelectric oxide solid solution, (Ca,La)₃Co₄O₉, and Ca₃Co₂O₆ which consists of 1D chains of alternating CoO₆ trigonal prism and CoO₆ octahedra. The reported La₂CaO₄ and the Ca-doped (La,Ca)₂CoO_4−z phases were not found at 885 °C. As a result of the absence of these phases, the phase diagram is significantly different from that reported at 1100 °C. Small solid solution regions of (La_1−xCa_x)₂O_3−z (0 ≤ x ≤ 0.08), (Ca_1−xLa_x)₃Co₄O₉ (0 ≤ x ≤ 0.07), and (La_1−xCa_x)CoO_3−z (0 ≤ x ≤ 0.2) were established.     

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 diagram study of CaBr2–CaHBr system

A study of binary, CaBr₂–CaHBr system was carried out by differential thermal analysis (DTA), covering the composition range from 100 % CaBr₂ to 100 % CaHBr between room temperature and 800 °C. From DTA results, the contour of solidus and liquidus temperatures with composition is plotted and the phase diagram of CaBr₂–CaHBr system is constructed. The system shows an eutectic reaction at 576 °C and the eutectic composition is 79.6 mol% CaBr₂. Co-existing phases in different phase fields are characterized by X-ray diffraction analysis.     

Phase diagram and dissolution studies of the fenofibrate–acetylsalicylic acid system

Enhancement of the dissolution rate of poorly soluble compounds through the formation of drug–drug eutectics was investigated using fenofibrate and acetylsalicylic acid. Solid–liquid equilibria in the system under study were investigated by differential scanning calorimetry (DSC). The phase diagram for the whole range of compositions was constructed. In addition, existence of a metastable polymorph of fenofibrate has been confirmed. The investigation has revealed that acetylsalicylic acid and fenofibrate form a simple eutectic mixture containing 0.958 mol fraction of fenofibrate at the eutectic point. Dissolution rate improvement of fenofibrate correlated with the phase diagram. The amount of fenofibrate released from the solid dispersions that contained fenofibrate as the eutectic mixture with acetylsalicylic acid was at least threefold higher compared to untreated fenofibrate.     

Phase diagram of the ethylene glycol-dioxane system in the temperature range from ?90 to 25°C

The ethylene glycol-1,4-dioxane system is studied by means of differential scanning calorimetry over a wide range of temperatures (?90 to 25°C) and is found to be a simple eutectic with the eutectic point at 10 mol % of dioxane (?16.5°C). Unlike a water-dioxane system, in which the clathrate with dioxane: H₂O = 1: 34 ratio is formed, the observed phase diagram showed no evidence of clathrate formation, due presumably to its hydrogen bond geometry and the intermolecular interaction properties of ethylene glycol.     

Phase diagram study of CaBr2–LiBr system using DTA

The phase diagram of binary LiBr–CaBr₂ system was investigated using differential thermal analysis (DTA) between room temperature and 800 °C. From the DTA results obtained over the entire range of composition from pure LiBr to pure CaBr₂ in steps of ~5 mol%, the phase diagram was constructed and is reported here. The results indicated the possible existence of a compound at 50 mol% LiBr, namely, LiCaBr₃. The compound undergoes peritectic decomposition at 552 °C. The system shows a eutectic reaction at 532 °C between this compound and LiBr phase, and the eutectic composition is close to 80 mol% LiBr. The compound LiCaBr₃ decomposes into CaBr₂ and LiBr phases below 272 °C. Co-existing phases in different phase fields are characterized by X-ray diffraction analysis.     

Phase diagram of ZnAs2–MnAs system

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Phase Transformations in the Mn–Ga–O System Depending on the Preparation Conditions

Manganese-gallium samples with cation ratios Mn:Ga = 1:2, 1.5:1.5, and 2:1 are synthesized by coprecipitation with subsequent annealing in air in a temperature range 600–1200 °C. Powder XRD, TEM, and BET methods are used to study the physicochemical characteristics of the samples. It is found that in the air at the annealing temperature of 600 °C finely dispersed low-temperature Mn_3–xGa_xO₄ spinels primarily form in all series, but in the whole temperature range (600–1200 °C) the system is multiphase. Annealing at 800–1200 °C leads to an increase in the concentration of simple oxides (β-Mn₃O₄ and β-Ga₂O₃). Only simple α-Mn₂O₃ and β-Ga₂O₃ oxides exist in a Mn:Ga = 2:1 series at 800 °C. In the sample with a cation ratio Mn:Ga = 1.5:1.5 annealed in air at 1000 °C, the formation of a superstructure based on the spinel structure is found.     

Phase relations in the vicinity of the compound YBa2Cu3O7 − δ at constant oxygen pressure

The phase relations in part of the BaOY₂O₃CuO system were investigated by differential thermal analysis coupled with thermographimetric measurements, X-ray and microprobe analysis, microstructural examinations in a light microscope and in a scanning electron microscope and inductive measurements of the superconducting transition temperatures. The superconducting compound YBa₂Cu₃O_{7 − δ} shows no homogeneity range with respect to the metallic constituents. Solidus temperature for the pseudobinary BaCuO₂CuO and formation temperatures for the compounds in the copper-rich part of the phase diagram are given.     

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.     

Thermodynamic assessment of phase diagram and concentration–temperature dependences of properties of solid solutions of the GaS–GaSe system

Journal of Thermal Analysis and Calorimetry - Before 100,000 years ago, during the Middle Stone Age (MSA) of South Africa, silica varieties of minerals and rocks were sometimes heated...     

Phase diagram for the system Bi2O3CaOSrOCuO in the SrO-rich region

It has been found experimentally that phase diagram for the system Bi₂O₃CaOSrOCuO in SrO-rich region at 850°C in the open air includes three elementary tetrahedra: CaOSrOSr₆Bi₂O₁₁Sr₂CuO₃, CaOSr₂CuO₃Sr₆Bi₂O₁₁Sr_3,5Ca_0,5Bi₂O₇ and Sr₃Bi₂O₆Sr₆Bi₂O₁₁Sr_3,5Ca_0,5Bi₂O₇ Sr₂CuO₃. In the considered interval of corresponding oxide concentrations quaternary oxides are not formed under the above conditions.     

Phase equilibria in the CsUO system in the temperature range from 873 to 1273 K

Portions of the cesium-uranium-oxygen system have been investigated between 873 and 1273 K and a phase diagram has been constructed using our data and the data of other workers in the field. A consistent set of measured and estimated thermodynamic data for cesium uranates has been used to calculate the equilibrium cesium partial pressure and the equilibrium oxygen partial pressure over two and three phase regions in the CsUO system. For a given temperature, the equilibrium cesium partial pressure in a two phase region decreases as the equilibrium oxygen partial pressure increases.     

Phase state diagram of a poly(amic acid)–solvent–nonsolvent system

Phase behavior and structure formation was studied using optical interferometry, nephelometry, and refractometry in the polymer–solvent–nonsolvent system for DMF solutions of two poly(amic acids): based on 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride and meta-phenylenediamine (PAA-1) and pyromellitic acid dianhydride and 4,4′-oxydianiline (PAA-2). Distilled water and its mixtures with DMF were used as a nonsolvent. According to the results of the study, isothermal cross sections of the phase state diagram in the threecomponent system were plotted, the position of the critical point, the spinodal, and the conodes were determined, the movement of the figurative points in the system was traced depending on the nonsolvent composition.     

Phase equilibria in the oxide system Nd2O3–K2O–P2O5

A phase equilibria diagram of the partial system NdPO₄–K₃PO₄–KPO₃ has been developed as part of the research aimed at determining the phase equilibrium relationships in the oxide system Nd₂O₃–K₂O–P₂O₅. The investigations were conducted using thermoanalytical techniques, X-ray powder diffraction analysis and reflected-light microscopy. Three isopleths existing between: K₃Nd(PO₄)₂–K₄P₂O₇, NdPO₄–K₅P₃O₁₀ and NdPO₄–K₄P₂O₇ have been identified in the partial NdPO₄–K₃PO₄–KPO₃ system. Previously unknown potassium-neodymium phosphate “K₄Nd₂P₄O₁₅” has been discovered in the latter isopleth section. This phosphate exists in the solid phase up to a temperature of 890 °C at which it decomposes into the parent phosphates NdPO₄ and K₄P₂O₇. Four invariant points: two quasi-ternary eutectics, E₁ (1057 °C) and E₂ (580 °C) and two quasi-ternary peritectics, P₁ (1078 °C) and P₂ (610 °C), occur in the NdPO₄–K₃PO₄–KPO₃ region.