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Title: Calculation of thermodynamic, electronic, and optical properties of monoclinic Mg2NiH4

Calculation of thermodynamic, electronic, and optical properties of monoclinic Mg2NiH4 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.
Authors: ; ; ;
Publication Date:
OSTI Identifier:OSTI ID: 793743
Report Number(s):LBNL--47519; OM-441
Journal ID: ISSN 0021-8979; JAPIAU; R&D Project: 474722; TRN: US200208%%91
DOE Contract Number:AC03-76SF00098
Resource Type:Journal Article
Resource Relation:Journal Name: Journal of Applied Physics; Journal Volume: 91; Journal Issue: 8; Other Information: Journal Publication Date: 15 April 2002; PBD: 1 Oct 2001
Research Org:Ernest Orlando Lawrence Berkeley National Lab., CA (US)
Sponsoring Org:USDOE Assistant Secretary for Energy Efficiency and Renewable Energy. Office of Building Technology, State and Community Programs. Office of Building Research and Standards (US)
Country of Publication:United States
Language:English
Subject: 08 HYDROGEN; 36 MATERIALS SCIENCE; ABSORPTION; DIELECTRIC MATERIALS; FUNCTIONALS; GEOMETRY; HYDROGEN; NEUTRON DIFFRACTION; OPTICAL PROPERTIES; THIN FILMS