Orthorhombic carbon oC48: A new superhard carbon allotrope

A new superhard carbon allotrope oC48 is uncovered. The mechanical and electronic properties of oC48 were studied by using first principles calculations. The calculated results of elastic constants and phonon dispersion show that oC48 is mechanically and dynamically stable. The hardness of oC48 is predicted to be 73.3 GPa, which indicates the superhardness of oC48. The elastic anisotropy of oC48 were also analyzed in detail. The band structure of oC48 shows that it is an indirect band gap semiconductor with a band gap of 1.464 eV. •A new orthorhombic superhard carbon oC48 was uncovered.•The hardness of oC48 is 73.3 GPa.•oC48 is a indirect band gap semiconductor.