Correlative Models for Perovskites with Rock Salt B-Site Ordering

Empirically derived predictive models describing synthesis-structure relationships have the potential to significantly improve and guide future research in a more cost-effective and timely manner; however, few of these models exist for cation ordering in perovskites. In this study, four compositions within the AZn_0.5Ti_0.5O₃ system (A = Nd, Sm, Nd_0.5La_0.5, Nd_0.5Gd_0.5) were synthesized using a conventional solid-state mixed-oxide method. X-ray diffraction data show evidence of long-range 1:1 rock salt cation ordering on the B site for all compositions. Additional data for other rock salt B-site ordered compositions were mined from literature. Correlative models for the B-site shrinkage (Δr_B) have been derived for each B-site ordered system, and a general model has been developed for rock salt B-site ordering from these specific models. This general model allows for the prediction of the room-temperature volume shrinkage resulting from rock salt B-site ordering using only published ionic radii data.