Hao Shiqiang, Delley Bernard, Veprek Stan, Stampfl Catherine
School of Physics, The University of Sydney, Sydney NSW 2006, Australia.
Phys Rev Lett. 2006 Aug 25;97(8):086102. doi: 10.1103/PhysRevLett.97.086102. Epub 2006 Aug 24.
Recently, a hardness similar to that of diamond has been reported for a quasiternary, nitride-based nanocomposite. The related, quasibinary nanocomposite "nc-TiN/a-Si3N4," which may be regarded as the prototype of the family of superhard nc-metal-N/a-Si3N4 systems, also exhibits a significant hardness enhancement. Extensive density-functional theory calculations indicate that the superhardness is related to the preferential formation of TiN(111) polar interfaces with a thin beta-Si3N4-derived layer. The strength of TiN in the 111 direction is similar to that of the weakest bonding direction in diamond. Oxygen impurities cause a significant reduction of the interface strength.
最近，据报道一种准三元氮化物基纳米复合材料具有与金刚石相似的硬度。相关的准二元纳米复合材料“nc-TiN/a-Si₃N₄”，可被视为超硬nc-金属-N/a-Si₃N₄系统家族的原型，也表现出显著的硬度增强。大量的密度泛函理论计算表明，超硬度与TiN(111)极性界面与薄的β-Si₃N₄衍生层的优先形成有关。TiN在111方向的强度与金刚石中最弱键合方向的强度相似。氧杂质会导致界面强度显著降低。
