Body centered cubic magnesium niobium hydride with facile room temperature absorption and four weight percent reversible capacity

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DOIResolve DOI: http://doi.org/10.1039/c2cp42136d
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TypeArticle
Journal titlePhysical Chemistry Chemical Physics
ISSN1463-9076
1463-9084
Volume14
Issue31
Pages1090410909
AbstractWe have synthesized a new metastable metal hydride with promising hydrogen storage properties. Body centered cubic (bcc) magnesium niobium hydride (Mg0.75Nb0.25)H2 possesses 4.5 wt% hydrogen gravimetric density, with 4 wt% being reversible. Volumetric hydrogen absorption measurements yield an enthalpy of hydride formation of −53 kJ mol−¹ H2, which indicates a significant thermodynamic destabilization relative to the baseline −77 kJ mol−¹ H2 for rutile MgH2. The hydrogenation cycling kinetics are remarkable. At room temperature and 1 bar hydrogen it takes 30 minutes to absorb a 1.5 μm thick film at sorption cycle 1, and 1 minute at cycle 5. Reversible desorption is achieved in about 60 minutes at 175 °C. Using ab initio calculations we have examined the thermodynamic stability of metallic alloys with hexagonal close packed (hcp) versus bcc crystal structure. Moreover we have analyzed the formation energies of the alloy hydrides that are bcc, rutile or fluorite.
Publication date
LanguageEnglish
AffiliationSecurity and Disruptive Technologies; National Research Council Canada
Peer reviewedYes
NPARC number21268940
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Record identifierdda04126-d142-4f04-be6f-e6ff57619079
Record created2013-11-27
Record modified2016-05-09
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