Release Time:2019-03-10  Hits:

Indexed by: Journal Article

Date of Publication: 2009-02-15

Journal: JOURNAL OF APPLIED PHYSICS

Included Journals: EI、SCIE

Volume: 105

Issue: 4

ISSN: 0021-8979

Key Words: ab initio calculations; density functional theory; diffusion; electronic structure; hydrogen storage; interstitials; pseudopotential methods; titanium compounds

Abstract: Hydrogen storage in TiCr2 alloy of AB(2) type with C15 Laves phase structure has been studied using density functional theory and plane-wave pseudopotential technique. The H atom interacts stronger with Cr atoms than with Ti and tends to occupy the g (2A2B) site due to the largest interstitial space. The g sites together with e (1A3B) sites form a three-dimensional clathratelike network, providing a diffusion pathway for H atoms, and the energy barriers for the H diffusion along these paths were computed. Interaction between two interstitial H atoms inside the TiCr2 lattice can be considered as a screened Coulomb repulsion, which seems to control the maximum hydrogen content in the metal hydrides. The absorption energies and electronic structures of metal hydrides TiCr2Hx with x=0.5-12 have been computed, and the theoretical maximum hydrogen storage capacity (between 2.6 and 3.8 wt %) agrees with experiments. The effects of the lattice expansion due to hydrogen absorption of different amounts have also been investigated.