Dilute Element Compounds: A Route To Enriching Inorganic Functional Materials

The development of functional materials calls for ever-enriching the inorganic material database. Doping is an effective way of achieving this purpose. Herein, we propose the concept of dilute element compounds (DECs), which contain a small amount of a dopant element distributed in a host crystal structure in an ordered manner. Different from dilute alloys or solid solutions, the DECs could be more resistant to segregation and are ideal for dispersing functional elements for applications such as single-atom catalysts. It is also expected that the DECs will serve as a route to discovering new inorganic functional materials by controlling phase transitions and tuning intrinsic properties of the host materials with applications including, but not limited to, thermoelectrics and solid-state electrolytes for secondary batteries. As an initial work, we quantify the diluteness of DECs and find the limits of diluteness in existing DECs. We further provide a classification scheme for the DECs to guide future discoveries.