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The phase diagram of the La-S-O system at 1073 K was established with the vacuum seal technique. Six phases exist at this temperature: La2O3 (B-type), LaS2, La2S3, La2O2SO4, La2O2S and La2O2S2. The thermodynamic functions for the reaction La2O2SO4=La2O3+SO2+1/2 O2 were determined by using the emf method at temperatures from 1123 to 1373 K. The mechanisms of the oxidation reactions in the La-S-O system under different partial pressures of oxygen (−4.4 < log <−0.7) were also investigated by means of DTA, TG and powder X-ray diffractometry.

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The ternary system CePO4−NaPO3−Ce(PO3)3 was investigated by differential thermal analysis, powder X-ray diffraction and microscopy in reflected light. Two double phosphates, NaCeP2O7 and NaCe(PO3)4, occur in this system. Both NaCeP2O7 and NaCe(PO3)4 melt incongruently, at 800 and 865°C, respectively. Two systems, NaCeP2O7−NaCe(PO3)4 and CePO4−NaCe(PO3)4, were found to occur in this region. Their phase diagrams are presented.

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Reaction calorimetry strongly penetrated process development laboratories in the fine chemicals industry. Applications of calorimetry to different fields of process optimization, chemical reactions and physical unit operations were developed. Applications were first developed in the field of process safety. The thermal data of reaction obtained in the calorimeters allow us to check if a reaction will be controllable at full scale under normal operating conditions and in case of equipment failure. Further, the accurate temperature control and heat flow measurement opened the door to more engineering related data, in the fields of phase equilibria like vapour liquid, solubilities, crystallization and also in the mixing techniques. Some examples of developments in these different fields will be reviewed.

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The V9Mo6O40−Cr2(MoO4)3 system has been investigated using the differential thermal analysis (DTA) and X-ray phase diffraction methods. The system has been found not to be a real two-component system over the whole component system.

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The solubility and the physicochemical properties (densities, viscosities, refractive indices, conductivities and pH) in the liquid-solid metastable system (NaCl-KCl-CaCl2-H2O) at 308.15 K have been investigated using the isothermal evaporation method, and the dry-salt phase diagram, water-phase diagram, and the diagram of physicochemical properties vs. composition in the system were plotted. One three-salt cosaturated point, three metastable solubility isotherm curves, and three crystallization regions corresponding to sodium chloride, potassium chloride and calcium chloride tetrahydrate were formed, and neither solid solution nor double salts were found. On the basis of the extended Harvie-Weare (HW) model and its temperature-dependent equation, the values of the Pitzer parameters β(0), β(1), C ϕ for NaCl, KCl and CaCl2, the mixing ion-interaction parameters θNa,K, θNa,Ca, θK,Ca, ΨNa,K,Cl, ΨNa,Ca,Cl, ΨK,Ca,Cl, and the Debye-Hückel parameter A ϕ and the chemical potentials of the minerals in the quaternary system at 308.15 K were fitted, and the predictive solubility based on the temperature-dependent equation and the chemical potentials of the minerals agrees well with the experimental data.

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Equilibrium solubility curves of the ammonium aluminium sulphate in aqueous solutions of sulphuric acid have been calculated using checked literature data and our own measurements. The concentration of sulphuric acid ranged from 0 to 23 mass%, temperature range between 20 and 60C has been extrapolated up to 75C by means of a thermodynamically based correlation method. The solubility correlation as well as the hydration analysis implied a possible destructuralization of solutions at higher acid concentrations.

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Phase equilibria up to solidus line in CuO–In2O3 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–In2O3 system in the equilibrium state.

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The thermogravimetric curve (TG) for the decomposition of carnallite (KCl · MgCl2 · 6H2O) at constant water vapor pressure (1 bar) was calculated from the phase diagram (solid-liquid equilibria) and vapor pressure data, and the calculated and experimental results were compared.

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The technique of differential barothermal analysis (DBA) combines the hot isostatic pressing technique and classical differential thermal analysis has been elaborated. This technique allows the study of the phase equilibria in the most of inorganic systems under pressure up to 200 MPa and temperatures up to 2000C. The Ni-base alloy with the solidus, liquidus, g-phase and carbides dissolution temperatures of 1328, 1390, 1272 and 1255C, accordingly, was chosen as a model material. By DBA technique the pressure coefficients of the above mentioned temperatures were established. The values of the obtained coefficients are 3-5 times larger than the melting point pressure coefficient for the pure Ni (the alloy base metal). The discussion of the data obtained is carried out.

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