First-principles calculation of electronic structure, bonding characteristic and bonding strength of TiN(111)/BN/TiN(111) interface

The nanocomposite 'nc-TiN/a-BN' as a representation of the family of super-hard nitride-based nanocomposites, which is a nanocomposite thin film material, exhibits a significant hardness enhancement as compared with the pure constituents. In this paper, first-principles calculations were performed to investigate the role of interfaces in the nanocomposite 'nc-TiN/a-BN', to which less attention has been paid up to now. In order to determine theoretically the stable interface configuration in 'nc-TiN/a-BN', 16 possible theoretical TiN(111)/BN/TiN(111) sandwich interface configurations have been constructed based on the structure characteristic of 'nc-TiN/a-BN'. It is found in this calculation that the most favorable interface configuration istop-top-BN, which is closely related to each B atom covalently bonding to its tetrahedrally coordinated N atoms in it. Its electronic structure is calculated. The calculated results show that the bonds at the interface in 'top-top-BN' configuration are covalent. Its interface bonding strength is higher than that between two 111 crystalline planes in slab TiN or bulk TiN.