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

Abstract

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: ΔH̅_La^∞ = ΔH̅_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.