Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (12): 2793-2798.doi: 10.3866/PKU.WHXB20112793


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
  • Supported by:

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

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