Thermodynamic Analysis of the Ternary La—Ni—O System.

Abstract

Abstract The available literature information on the thermodynamic properties and phase equilibria for the La–Ni–O system has been critically assessed. Based on the known thermodynamics of the boundary systems La–Ni, La–O, and Ni–O models have been defined to describe the Gibbs energy of the individual phases, and the model parameters have been optimized by least-squares fit to the selected experimental information of different kind (phase diagram data, calorimetric data, and equilibrium oxygen pressures) using the CALPHAD-method (calculating phase diagrams). A self-consistent set of Gibbs energy functions describing the La–Ni–O system, which contains four ternary phases La 2 NiO 4 , La 3 Ni 2 O 7 , La 4 Ni 3 O 10 , and LaNiO 3 that are all treated as stoichiometric compounds has been obtained for the first time. Various phase diagrams and thermodynamic properties have been calculated and are compared with the experimental measurements. Possible directions for the future work are discussed.