Underpinning the relationship between synthesis and properties of high entropy ceramics: A comprehensive review on borides, carbides and oxides

This work reviews the recent development of High Entropy Ceramics (HEC), which have five or more elements combined in equimolar or near equimolar quantities and have demonstrated unique properties. The comprehensive review is based on the general classifications of high entropy ceramics into carbides, borides, oxides, and other ceramic compounds. For each class of HECs, the synthesis processes, microstructure, and mechanical, thermal, and electrical properties are summarized in detail, with property data tables. Additionally, the fabrication and properties of HEC in the form of film, coatings, and composites are discussed. In addition to these material properties, this review article also highlights the utilization of computational studies and machine learning (ML) in the discovery of high entropy carbides. Finally, the overall conclusion of the current status and future research direction are discussed.