物理化学学报 >> 2011, Vol. 27 >> Issue (12): 2793-2798.doi: 10.3866/PKU.WHXB20112793

理论与计算化学 上一篇    下一篇

Mg-Ti-H 体系晶体结构与相稳定性的第一性原理计算

杜晓明1, 李武会2, 黄勇1, 吴尔冬2   

  1. 1. 沈阳理工大学材料科学与工程学院, 沈阳 110159;
    2. 中国科学院金属研究所, 沈阳 110016
  • 收稿日期:2011-05-20 修回日期:2011-08-22 发布日期:2011-11-25
  • 通讯作者: 杜晓明 E-mail:du511@163.com
  • 基金资助:

    辽宁省博士启动基金(20091066)资助项目

First-Principles Calculation of the Crystal Structure and Stabilization of Mg-Ti-H System

DU Xiao-Ming1, LI Wu-Hui2, HUANG Yong1, WU Er-Dong2   

  1. 1. School of Material Science and Engineering, Shenyang Ligong University, Shenyang 110159, P. R. China;
    2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
  • Received:2011-05-20 Revised:2011-08-22 Published:2011-11-25
  • Contact: DU Xiao-Ming E-mail:du511@163.com
  • Supported by:

    The project was supported by the Scientific Research Starting Foundation for Doctoral Program of Liaoning Province, China (20091066).

摘要: 采用基于密度泛函理论的第一性原理赝势平面波方法计算了不同Ti 含量的MgxTi(1-x)H2 (x=0.25, 0.5,0.75, 0.875)体系的平衡晶格结构、总能量及稳定性. 结果表明: 氢原子在晶胞中的位置接近于四面体间隙位置; H―Ti 原子间距小于H―Mg原子间距, 表明Ti 较Mg具有更强的“亲氢性”, Ti 原子在吸引周围H原子的同时削弱了H―Mg键的强度; 随Ti 含量的增加, 体系的稳定性和脱氢温度均降低, 且MgxTi(1-x)H2体系与MgH2相比,稳定性更差, 脱氢温度更低, 表明Ti 可降低MgxTi(1-x)H2体系的分解温度并加速其脱氢动力学过程, 表现出脱氢催化活性.

关键词: MgxTi(1-x)H2, 晶体结构, 赝势平面波, 稳定性

Abstract: First-principles calculations were performed to determine the equilibrium crystal structures, energetic properties, and stability of MgxTi(1-x)H2 (x=0.25, 0.5, 0.75, 0.875) systems containing different amounts of titanium using the pseudopotential plane-wave method based on density functional theory. The calculation results show that the hydrogen atoms in the MgxTi(1-x)H2 hydrides roughly occupy the tetrahedral interstitial sites. The calculated H―Ti distances are less than the H―Mg distances. This indicates that Ti has a more notable affinity for hydrogen than Mg. The bonding strength of H―Mg is weaker when the Ti atom attracts surrounding hydrogen atoms. The stabilization and dehydrogenation temperatures of the hydrides MgxTi(1-x)H2 are lower than those of MgH2 with an increasing Ti content. This indicates that titanium can reduce the decomposition temperature of the MgxTi(1-x)H2 hydrides and play a significant catalytic role in improving the dehydrogenation dynamic properties of the MgxTi(1-x)H2 hydrides.

Key words: MgxTi(1-x)H2, Crystal structure, Pseudopotential plane-wave, Stabilization

MSC2000: 

  • O641