An orthorhombic carbon allotrope with a quasi-direct band gap and superhard

A 3-dimension orthorhombic symmetry carbon allotrope structure oP10 carbon with space group Pmma is investigated based on density functional theory. The oP10 carbon is theoretically more favorable in enthalpy than most other carbon allotropes. At the same time, oP10 carbon possesses dynamic stability and mechanical stability. The elastic moduli (Young's modulus E is 928 GPa, bulk modulus B is 390 GPa, and shear modulus G is 421 GPa) of oP10 carbon are greater than those of c-BN. oP10 carbon shows that the stress response in the [001], [010], and [100] directions is between 105.3 GPa and 136.0 GPa, proving that oP10 carbon is a potential superhard material. The oP10 carbon exhibits different degrees of mechanical anisotropy, and all the mechanical anisotropy factors increase with increasing pressure. In addition, oP10 carbon is a quasi-direct and wide band gap semiconductor material. Based on the excellent mechanical and electronic properties of oP10 carbon, it may be used in cutting tools and microelectronic applications such as photodetectors. [Display omitted] •oP10 carbon is a quasi-direct band gap semiconductor material.•oP10 carbon is a superhard material with hardness of ~72 GPa.•All the stress response in the [001], [010], and [100] directions exceed 100 GPa.