High‐entropy oxides based on valence combinations: design and practice

Abstract High‐entropy oxides (HEOs) are a new class of materials promising for a wide range of applications. Designing HEOs needs to consider both geometric compatibility and electrical balance. However, there is currently no available method to systematically consider these two factors when selecting constituent materials for making HEOs. Here we propose a two‐step strategy, where a HEO system is first partitioned into multiple subsystems based on the valence combinations of constituted cations; the geometric compatibility is then considered in selecting suitable constituted cations. We demonstrate this strategy by using A(5B 0.2 )O 3 perovskite as a model system. We show that the system can be partitioned into 12 subsystems. A single‐phase cubic perovskite has been synthesized in ten of the subsystems. We anticipate that this strategy is applicable to other oxide systems.