Thermodynamics of phase stability and disorder in Inter-Lanthanide ternary ABO3 oxides from first principles

Inter-lanthanide ternary oxides (IL-ABO3) find application in various technological fields due to their diverse properties and flexible chemistries that are readily synthesizable in multiple crystal structures. Here, we investigate the chemistry-dependent thermodynamic formability and the tendency to disorder for IL-ABO3 (A, B = La–Lu) compounds having different structures using density functional theory. We reproduce the previously observed relationship between the IL-ABO3 crystal structure and difference in the A and B ionic radii. We investigate the formation of metastable phases, finding a region of IL-ABO3 chemistries with rich metastability in a small energy interval. We analyze the influence of disordering on the stability of the ground state structures, correlating the propensity for disorder with the energy difference between different cation orderings. Our results provide fundamental insights into the phase stability of IL-ABO3, the energetics of their metastable structures, and their tendency to disorder, paving the way towards their broader technological applicability.