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 characterisric of 'nc-TiN/a-BN'. It, is found in this calculation that the most favorable interface configuration is 'top-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.