Ima2 C32: An orthorhombic carbon allotrope with direct band gap

Abstract

Ima2 C32 with sp2 + sp3 hybridized network is proposed in this work, and the structural properties, electronic properties, absorption spectra, elastic properties, elastic anisotropy properties, and stability of Ima2 C32 are studies by density functional theory. Ima2 C32 is dynamically stable, thermodynamically stable, and mechanically stable. The shear modulus and bulk modulus, and Young's modulus of Ima2 C32 is 217 GPa, 267 GPa, and 512 GPa, respectively, all them are smaller than that of diamond, while Young's modulus, shear modulus and bulk modulus of Ima2 C32 is larger than that of C24-C and C24-D in sp2 + sp3 hybridized structures. Ima2 C32 is a direct and wider band gap semiconductor material. The visible light absorption ability of Ima2 C32 is slightly better than C24-D, cubane-yne, and T carbon. Due to the direct band gap and the stronger visible light absorption ability, Ima2 C32 might be used in the optoelectronic devices. In addition, the elastic anisotropy properties of Ima2 C32 are also investigated in this work. The Poisson's ratio are negative in (0 0 1), (1 −1 0), (1 1 0), (1 0 1), and (1 1 1) planes.