First-principles study of structural,electronic,elastic,and thermal properties of Imm2-BC

Using the first-principles method, we predict an orthorhombic boron–carbon binary structure with sp~ace group Imm2.This structure is verified to be dynamically and mechanically stable, and possesses a cavity of 27.5 ~2 that makes it a potential molecular sieve material. The C sp~2 and sp~3 hybridized bonding in Imm2 BC is an important factor for its structural stability. The energy band calculations reveal that Imm2 BC is a semiconductor with a band gap of 1.3 eV and has a promising application in the electro-optic field. The lattice thermal conductivity along the crystal [100] direction at room temperature is 186 W·m-1·K-1, that is about 5 times higher than those along the [010] and [001] directions, which stems from the different group velocity along the crystal direction. Moreover, the acoustic-optical coupling is important for heat transp~ort in Imm2 BC, and the contribution of optical phonons to lattice thermal conductivity in the [100], [010], and [001]directions is 49%, 59%, and 61%, resp~ectively. This study gives a fundamental understanding of the structural, electronic,elastic, and heat transp~ort properties in Imm2 BC, further enriching the family of boron–carbon binary compounds.