High-entropy stoichiometric perovskite oxides based on valence combinations

The valence-combination strategy was applied to design B-site substitution non-equimolar stoichiometric high-entropy perovskite oxides (HEPOs). 29, 56 and 29 valence combinations with the maximum configurational entropy higher than 1.5R for five-component HEPOs were identified when the average valence of B-site is 3, 4 and 5, respectively. Synthesis experiment was performed on 8 valence combinations with the average valence of B-site equal to 4. Single-phase HEPOs were obtained from 6 of them. It was also found that most of HEPOs have ordered structures. The formation of single-phase HEPO and ordered structure was discussed in terms of structural tolerance factor and valence-difference factor.