Synthesis of (bi0.2ln0.2sr0.2k0.2na0.2)tio3 High-Entropy Perovskite Oxides Containing Ln Element

High-entropy perovskite oxides have attracted significant attention owing to their excellent performance and diverse application potential. This study reports the synthesis of (Bi0.2Ln0.2Sr0.2K0.2Na0.2)TiO3 high-entropy perovskite oxides containing Ln element. The results indicate that seven of the 13 compositions with a larger ionic radius of Ln3+ can be prepared as single-phase high-entropy perovskites. During the formation of high-entropy perovskites, the Ln2Ti2O7 pyrochlore or pyrochlore-like phase first forms as an intermediate phase. The formation of a single high-entropy perovskite phase depended on the complete dissolution of the Ln2Ti2O7 pyrochlore or pyrochlore-like phase within the perovskite matrix. The pyrochlore phase content depends on the stability of this intermediate pyrochlore phase, related to the ionic radii ratio of Ln3+ and Ti4+. These findings provide guidance for judicious elemental selection in high-entropy perovskite oxides.