B

The search of new superhard materials with Vickers hardness larger than 40 GPa or even comparable to that of diamond remains considerably experimental and theoretical challenges. In this work, we have theoretically designed a potential superhard material in the ternary B-C-O system, B2CO, which is isoelectronic with diamond, by using the particle swarm optimization technique for crystal structure prediction. We find that B2CO stabilizes in a diamond-like structure with typically strong covalent sp3 B-C and B-O bonds. The calculated Vickers hardness of B2CO is ∼50 GPa, much higher than that (38 GPa) of B2O. Our research opens up a possibility to quest superhard materials within the ternary B-C-O system