Superhard B2CO phases derived from carbon allotropes

Abstract

Two new orthorhombic B2CO structures (oP16- and oC16-B2CO) have been predicted theoretically by manual construction. The calculations of independent elastic constants and phonon dispersion spectra have confirmed the mechanical and dynamical stabilities of oP16- and oC16-B2CO at zero pressure. Their formation enthalpies are both negative and lower than several B2CXO (X = 1, 2, 3, 5) phases, suggesting they are thermodynamically stable. Based on first-principles calculations, oP16- and oC16-B2CO are both superhard materials with indirect band gaps. With excellent hardness and tunable band gaps, B2CO will attract extensive attention for industrial applications and scientific research.