Calculation of Thermodynamic, Electronic, and Optical Properties of Monoclinic Mg2NiH4

Publication Type

Journal Article

Date Published

04/2002

LBNL Report Number

LBNL-47519

Abstract

Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.

Journal

Journal of Applied Physics

Volume

91

Year of Publication

2002
4879

Issue

8

Pagination

4879-4885