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Abstract  

Phase equilibria in the partial system Mg2P2O7−Na8Mg6(P2O7)5−NaPO3−Mg(PO3)2 were examined by differential thermal analysis and powder X-ray diffraction. It was found that there are six sections in the composition range under investigation.

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Abstract  

UV-Vis spectra of solutions in solid-aqueous phase equilibrium with UO3·2H2O(s) and 0.03 kPa CO2 partial pressure are quantitatively analyzed by single component spectra of hydrolysis species UO 2 2+ (aq), (UO2)2(OH) 2 2+ and (UO2)3(OH) 5 + . From the deconvoluted spectra, single species concentrations are obtained and interpreted by various statistical methods. Relationship of UV-Vis data to fluorescence spectroscopic analysis of the same system is discussed. Calculation of thermodynamic quantities gave consistent results, both within experimental data and with results from solubility studies and spectroscopic analysis from literature. A reinterpretation of some literature data is proposed.

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The present paper forms part of a series of studies on the ternary system PbO-P2O5 -PbCl2. The side binary system PbO-PbCl2 has been investigated over the entire composition range and its phase diagram has been established. The components form three oxychlorides: Pb5Cl2O4, Pb3Cl2O2 and Pb2Cl2O. The examinations were carried out by means of thermal, microscopic, dilatometric, X-ray and IR absorption analyses. X-ray identification data for Pb5Cl2O4 are presented.

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The system CePO4 — NaPO3 was investigated by differential thermal and X-ray analyses and infrared spectroscopy and its phase diagram was established. The system contains only one intermediate compound, NaCeP2O7, which melts incongruently at 800°. It exhibits a polymorphic transition at 595°. The low-temperature modification has an orthorhombic unit cell with the parameters.a=5.28,b=12.65,c=4.31 Å,a=β=γ=90° andV= 288.1 Å3.

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Abstract  

The phase diagram of the system Ag4SSe-SnTe is studied by means of X-ray diffraction, differential thermal and metallographic analyses and measurements of the microhardness and the density of the material. This diagram is divided into two eutectic-type subdiagrams by the composition Ag4SSe·2SnTe. The unit-cell parameters of the intermediate phases 3Ag4SSe·SnTe (phase A) and -Ag4SSe·2SnTe (phase B) are determined as follows: for phase A: a=0.7851 nm, b=0.7196 nm, c=0.6296 nm, =101.32°, =85.90°, =111.36°; for phase B: a=0.3662 nm, b=0.3303 nm, c=0.3343 nm, =90.74°, =108.94°, =91.91°. The phase Ag4SSe·2SnTe melts congruently at 615°C and a polymorphic transition of the phase takes place at T - =110°C.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Vassilev, Z. Boncheva-Mladenova, Pl. Patev, and S. Aleksandrova

The phase diagram of the Ag2Te-Cd system, which is a polythermal section of the ternary system Ag-Cd-Te, was established by means of DTA and metallographic analysis. The diagram contains 32 phase regions, including the polymorphic modifications of Ag2Te, solid solutions based on Ag2Te and Cd, and two intermediate phases with variable compositions: Ag2Cd1+xTe and Ag2Cd5+xTe.

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Abstract  

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 Δm 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.

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The liquid — liquid and liquid — solid equilibrium temperatures are taken for the binary systems octadecanol + A (A=dicarboxylic acids, biphenyl or (K, Na) stearate). The results are discussed and a relation connecting the composition of the eutectics with the thermodynamic properties of fusion of the components is derived from the ideal equation and compared with the experimental one.

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Abstract  

Values of the Flory-Huggins interaction parameters c were predicted on the base of mixing enthalpy H M for nitrocellulose-s-diethyldiphenylurea system. The phase diagram of the system and the glass transition temperature of mixtures T g12 were estimated using calculated c parameters. The predicted glass transition temperatures were in accordance with values determined experimentally.

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Abstract  

The phase equilibria established in the system Al2 (MoO4 )3 –V2 O5 throughout the whole component concentration range up to 1000C were investigated by DTA and XRD methods. The results are presented in the form of a phase diagram.

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