过渡金属氮化物中单原子固溶和力学性能的第一性原理研究

基于密度泛函理论(DFT)的第一性原理,计算Si原子在Ti族和V族氮化物中以及B、C和Ge原子在TiN晶体中固溶的稳定结构,讨论置换型和间隙型固溶的低能量稳定结构与晶体间距的关系,研究金属氮化物和固溶原子固溶结构的力学性能.结果表明:Si原子在TiN、ZrN、HfN和TaN晶体中固溶以及Ge原子在TiN晶体中固溶情况为,单原子不进入对应过渡金属氮化物晶体中形成间隙固溶或置换固溶,随着晶体间距离变化单原子可以在晶体之间形成间隙固溶或置换固溶;Si原子在NbN以及B原子在TiN晶体中可以实现间隙固溶,而不能形成置换固溶;Si原子在VN和C原子在TiN晶体中固溶结构形式均为置换固溶.单原子固溶形成低能量置换型固溶体和间隙型固溶体的弹性常数、体模量和剪切模量均低于原过渡金属氮化物的对应值.

Solid Solution Structure and Elastic Modulus of Single Atom in Transition Metal Nitrides: First Principle Studies

In order to investigate interface structure of composite films,several solid solution structures and elastic properties of a single atom in transition metal nitrides are studied with first principle method based on density functional theory.The calculation shows interesting results:(1) A silicon atom could not form a solid solution in TiN,ZrN,HfN,or TaN crystallites.It is the same for a germanium atom in TiN crystallite.(2) As distance between crystallites becomes large,a silicon atom in TiN,ZrN,HfN and TaN or a germanium atom in TiN may form interstitial or substitution interface structures.(3) A silicon atom in NbN or a boron atom in TiN could form interstitial or substitution interface structures.(4) Interface structures of a silicon atom in VN or a carbon atom in TiN is a substitution structure.Studies of mechanic properties indicate that modulus of elastic,bulk,shear and Young's of lower energy substitution and interstitial solid solution is less than that of transition metal nitrides.