Thermodynamic characteristics and phase equilibria in the alloys of the Ge–La system

• Published in: Russian Journal of Physical Chemistry A 2017-08, Vol.91 (8), p.1380-1387
• Main Authors: Shevchenko, M. A., Kudin, V. G., Sudavtsova, V. S., Ivanov, M. I., Berezutskii, V. V.
• Format: Article
• Language: English
• Subjects: Alloy systems; Chemical Thermodynamics and Thermochemistry; Chemistry; Chemistry and Materials Science; Enthalpy; Heat measurement; Melts; Phase equilibria; Physical Chemistry
• ISSN: 0036-0244; 1531-863X
• DOI: 10.1134/S0036024417080313

Mixing enthalpies of melts of the Ge–La system have been measured using isoperibolic calorimetry within two concentration ranges. For the first range (0 < x La < 0.16 at 1520 K and 0.16 < x La < 0.29 at 1570 K), agreement with the known literature data is observed within the experimental error. The second range (0.78 < x La < 1 at 1470 K and 0.7 < x La < 0.78 at 1580 K) has been studied for the first time. The melts are characterized by very strong exothermal effects of mixing, which have almost symmetrical concentration dependence: Δ H̅ La ∞ = Δ H̅ Ge ∞ = −245 kJ/mol at 1470 K. A thermodynamic optimization of the activities of the components and the phase diagram of the system have been conducted based on the obtained experimental data, using an ideal associated solution (IAS) model.