First-principles calculation of structural and electronic properties of Ti-doped B13C2

Stability and electronic properties of Ti-doped boron carbides (B13C2) were studied using the first principle calculations based on plane wave pseudo-potential theory. The calculated results showed that Ti atom doped in boron carbide was in preference to substituting C atom on the end of chain C-B-C, but it was difficult for Ti to substitute B atom in the center of the chain C-B-C or in the icosahedron. A representative stable structural unit containing Ti atom was [C-B-Ti]ɛ+-[B11C]ɛ-, while the structural unit without Ti was [C-B-C]ɛ--[B12]ɛ+. The band structure and density of states (DOS) indicated that the coexistence of [C-B-Ti]ɛ+-[B11C]ɛ- structural unit made electrical conductivity increased. As the covalent bond of Ti-B was weaker than those of B-B and B-C, the thermal conductivity decreased for Ti-doped B13C2, thermoelectric property of Ti-doped boron carbides has been improved.