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Author Kunkel, Nathalie ♦ Reichert, Christian ♦ Springborg, Michael ♦ Wallacher, Dirk ♦ Kohlmann, Holger
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ CRYSTALS ♦ DECOMPOSITION ♦ DEUTERIUM ♦ HYDROGEN ♦ HYDROGENATION ♦ LITHIUM HYDRIDES ♦ NEUTRON DIFFRACTION ♦ SOLID SOLUTIONS
Abstract In-situ neutron powder diffraction studies of the Half-Heusler phase LiAlSi under high deuterium pressures and first principle calculations of solid solutions of Li{sub x}Sr{sub 1−x}AlSi and their hydrides Li{sub x}Sr{sub 1−x}AlSiH were carried out. In contrast to an earlier study, there is no experimental evidence for hydrogen (deuterium) uptake up to gas pressures of 15 MPa and temperatures of 550 °C. Instead a slow decomposition reaction according to LiAlSi+1/2H{sub 2}=LiH+Al+Si was found by in-situ neutron powder diffraction. Theoretical calculations by DFT methods on hypothetical solid solutions of Li{sub x}Sr{sub 1−x}AlSi show the LiAlSi type to be the energetically most stable structure for 0.7<x and the SrAlSi type structure for lower values of x. Hydrides Li{sub x}Sr{sub 1−x}AlSiH favor the SrAlSiH type for all values of x instead of the structure proposed earlier with hydrogen occupying tetrahedral voids in a LiAlSi structure. As an alternative for a cubic structure for LiAlSiH, we suggest the existence of LiAlSiH in the trigonal SrAlSiH type structure and it might be a candidate worthwhile to be considered for preparative work. - Graphical abstract: In-situ neutron powder diffraction of LiAlSi under high D{sub 2} pressure. - Highlights: • In-situ neutron powder diffraction of LiAlSi under high D{sub 2} pressure was carried out. • LiAlSi decomposes according to LiAlSi + ½ H{sub 2} = LiH + Al + Si. • Mixed crystals Li{sub x}Sr{sub 1-x}AlSi and LixSr{sub 1-x}AlSiH were studied theoretically.
ISSN 00224596
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-01-15
Publisher Place United States
Journal Journal of Solid State Chemistry
Volume Number 221


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