Research progress of high hardness B-C-O compounds

Hard materials are widely used in industrial processing and basic scientific research. It is of great significance to design new lightweight and high hard materials. In current review, the experimental research progress of B-C-O compounds were firstly introduced, afterwards is the theoretical study of B-C-O compounds. Depending on the difference of composition and structure, the sp3 hybrid tetragonal B2CO superhard phase, sp3 hybrid orthogonal B2CO superhard phase, sp3 hybrid monoclinic B2CO hard phase, sp2-sp3 coexistence B2CO with high-hard structure, carbon-rich diamond isoelectronic compounds B2CXO superhard phase, non-diamond isoelectronic system B-C-O compounds high hard structure are all described including crystal structure, stability analysis, mechanical properties, and so on. Whereafter, the influence of structure and composition on their properties has been analyzed. Finally, the shortcomings of current research are dissected and suggestions for the theoretical design and experimental synthesis of B-C-O compounds with high hardness are put forward.