Thermodynamic Properties and Vaporization Processes in the La2C3–C System

Abstract

Vaporization processes of the components in the La₂C₃–C system were studied by Knudsen effusion mass spectrometry in the temperature range of 2196–2435 K. The main vapor species over the system under study were La and LaC₂. The temperature dependences of the partial pressures of the identified vapor species and of the La activity, as well as the La and LaC₂ partial molar enthalpies of vaporization, were determined in the La₂C₃–C system. It was shown that the found values of thermodynamic properties are in agreement with the literature data and with the results of modeling using the NUCLEA database for the LaC₂–C system. This allowed the thermodynamic properties of the LaC₂–C system to be evaluated on the basis of the obtained values. It was established that the La activity is independent of temperature, indicating a zero La partial molar enthalpy of mixing in the region of the LaC₂ and C equilibrium. The results of this study can be further used to supplement thermodynamic databases and to optimize phase diagrams of multicomponent carbide systems that are promising for various high-temperature technologies.