TiC陶瓷中H原子扩散行为第一性原理计算研究

采用第一性原理计算方法研究了H原子在立方TiC 晶格中的结构稳定性及扩散行为。结果表明：H原子在TiC晶格中的最稳定位点位于Ti/C六面体中靠近C原子的C-H（C-HS）位置，H被C原子捕获而形成C—H键，键长1.15 Å（1 Å=0.1 nm），零点修正（ZPE）后形成能为1.58 eV；其次是Ti/C六面体中心位置（CS），H 原子主要与Ti原子成键，ZPE修正后的形成能为1.75 eV。采用CI-NEB方法计算预测了TiC晶格中H间隙原子的最优扩散路径，即先在Ti/C六面体内沿(110)晶面进行“跳跃”扩散，扩散势垒为0.47 eV；然后以C原子为中心，沿(100)晶面进行两次“旋转”扩散穿越Ti/C原子面，扩散势垒为0.28 eV。

Diffusion Behavior of H Atom in TiC Ceramic by First-Principles Calculations

The structure stability and diffusion behavior of interstitial hydrogen in stoichiometric TiC bulk are investigated by first-principles calculations. The results indicate that interstitial hydrogen in stoichiometric TiC bulk prefers to be trapped by the C atom(C-HS) with C—H bond length of 1.15 Å(1 Å=0.1 nm), and its formation energy is 1.58 eV after ZPE correction, followed by the center position of Ti/C cube(CS) with formation energy of 1.75 eV after ZPE correction. The hydrogen in CS configuration is mainly hybridized with neighboring Ti atoms. The optimal diffusion path of interstitial hydrogen in TiC bulk is consisted by the “jumping” diffusion in Ti/C cube with energy barrier of 0.47 eV, then followed by twice “rotating” diffusion through Ti/C plane with energy barrier of 0.28 eV.