Thermodynamic properties and high-temperature evaporation of gadolinium silicides in vacuum

Using the methods of mass-spectrometric and x-ray diffraction analysis to investigate their high-temperature evaporation in vacuum, it was determined that gadolinium silicides undergo the sequence of phase transformations Gd₅Si₃ → Gd₅Si₄ → GdSi. The enthalpies of the phase transformations were calculated, as well as the enthalpies of formation of the silicides (?116.6, ?521.6, and ?502.5 kJ/mole for GdSi, Gd₅Si₄, and Gd₅Si₃, respectively). The results obtained are compared with data in the literature.     

Thermodynamic properties of manganese silicides

Summary The free energies, heats, and entropies of formation of the manganese suicides between 950 and 1100°K were measured by means of the emf method.     

Thermodynamic properties of condensed silicides

An approximate generalized equation is obtained for the temperature dependence of the change in Gibbs energy in the atomization of condensed silicides; this equation takes account of the number of atoms present in the silicides and their calculated boiling points. For the 16 silicides considered, the discrepancy between the maximum calculated value and the mean is no more than 10%. On that basis, the proposed method may be used to verify data from other sources and also for approximate prediction of the thermodynamic properties of silicides that have not yet been studied.     

Thermodynamic properties of chromium silicides

Conclusions The method of measuring the emf's of high-temperature galvanic cells was employed for determining the isobaric-isothermal potentials, entropies, and heats of formation of the chromium silicides CrSi₂, CrSi, Cr₅Si₃, and Cr₃Si in the temperature range 700–850°C. Using literature data upon the enthalpies and entropies of the chromium silicides and pure chromium and silicon, the standard heats and entropies of formation of these silicides were calculated.Translated from Poroshkovaya Metallurgiya, No. 7 (115), pp. 61–65, July, 1972.     

Thermodynamic properties of silicides of alkaline-earth metals

The standard formation enthalpies, entropies, and enthalpies, and heat capacities in the range from 298.15 K to the melting point T_m are calculated for magnesium, calcium, stronium, and barium silicides.     

Thermodynamic properties of lanthanum silicides at high temperatures

The enthalpies of five lanthanum silicides were determined over the temperature range 380–2225 K by the method of mixtures. Values of the basic thermodynamic functions of the materials were calculated and tabulated, as well as the temperatures, enthalpies, and entropies of fusion. The temperatures and enthalpies of fusion were related to the relative concentrations of silicon in the compounds.Institute of Materials Science Problems, Ukrainian National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 3–4, pp. 48–53, April–May, 1994.     

Thermodynamic properties of La2C3 and Gd2C3 at high temperatures

The enthalpies of lanthanum and gadolinium sesquicarbides were determined in the range 400–1900 K by the method of mixtures. The temperature dependences of the basic thermodynamic properties were calculated and tabulated. The temperatures, enthalpies, and entropies of the peritectic reactions were determined. Institute for Meterials Science Problems, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8, pp. 59–63, July–August, 1997.     

Magnetocaloric properties of the Gd5Si2.05-xGe1.95-xMn2x compounds

The influence of the manganese-alloying on the structure and magnetocaloric properties of the Gd5Si2.05Ge1.95 compound was studied by X-ray powder diffraction and magnetization measurements.The Gd5Si2.05-xGe1.95-xMn2x(2x=0,0.03 and 0.08) compounds crystallized in the Gd5Si2Ge2-type monoclinic structure.In all X-ray powder diffraction patterns,a minor hexagonal Gd5Si3 phase was observed as a second phase.With increasing Mn content,the unit cell volume increased.For the compounds with x=0,0.03 and 0.08,the fi...