摘要
建立不同类型的原子团簇模型,利用电荷自洽离散变分法计算了Ti薄膜中不同晶体结构的原子间化学键键能,分析了薄膜中晶体的局域态密度和全态密度,探讨了其电子结构和Ti-N原子间的交互作用变化.结果表明,N原子占据八面体间隙中心位置后,强Ti-N键的形成和原有Ti-Ti键的弱化,促使hcp-Ti中(00.1)面上的Ti原子沿着<01.0>方向发生迁移,成为hcp-fcc相变中fcc-Ti亚晶格形成的根源.随着进入hcp-Ti晶格中N原子数的增多,Ti-N结合键数目增加,N 2p/Ti 3d-4p杂化价电带的电子密度也随之增大,Ti的外层电子平均能量降低,保证了fcc-TiNy的稳定生长.
Different atomic cluster models were established and employed for calculations by the self-consistent-charge discrete variational Xα method.Chemical bond energies between atoms of various crystals in Ti thin film were calculated,and their electronic structures and Ti-N atomic interactions were discussed with the local and total density of state curves.The results show that forming of strong Ti-N bonds and weakening of initial Ti-Ti bonds promote those Ti atoms in the(00 · 1) plane of hcp-Ti to shift towards the <01 · 0> direction with respect to occupation of N atoms at the octahedral sites,which is considered to be the origin for the hcp-fcc transformation of Ti sublattices.With the number of N atoms invaded in the hcp-Ti crystal lattice increasing,the number of Ti-N bonds increases.Subsequently,the electron density in the valence band hybridized by N 2p and Ti 3d-Ti 4p states increases gradually with increasing dose of N,and accordingly the average energies of occupied states for outer-shell electrons of Ti are lowered due to the hybridization.This reduction in the average energies gives rise to the higher stability of fcc-TiNy in Ti thin film.
出处
《材料与冶金学报》
CAS
北大核心
2012年第3期207-211,共5页
Journal of Materials and Metallurgy
基金
中央高校基本科研业务费专项资金资助项目(N090402005)
国家自然科学基金青年基金资助项目(50901016)
关键词
氮化
Ti薄膜
原子团簇
电荷自洽离散变分法
电子结构
杂化轨道
nitriding process
Ti thin film
atomic cluster
self-consistent-charge discrete variational Xα method
electronic structure
hybridization
