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Title: High-pressure polymorphism as a step towards high density structures of LiAlH{sub 4}

Two high density structures β- and γ-LiAlH{sub 4} are detected in LiAlH{sub 4}, a promising hydrogen storage compound, upon compression in diamond anvil cells, investigated with synchrotron X-ray diffraction and first-principle calculations. The joint of the experimental and theoretical results has confirmed the sequence of the pressure-induced structural phase transitions from α-LiAlH{sub 4} (space group P2{sub 1}/c) to β-LiAlH{sub 4} (P2{sub 1}/c-6C symmetry), and then to γ-LiAlH{sub 4} (space group Pnc2), which are not reported in previous literatures. At the α to β transition point for LiAlH{sub 4}, the estimated difference in cell volume is about 20%, while the transformation from β to γ phase is with a volume drop smaller than 1%. The α to β phase transition is accompanied by the local structure change from a AlH{sub 4} tetrahedron into a AlH{sub 6} octahedron, which contributes to a large volume collapse.
Authors:
; ; ; ; ; ; ; ; ;  [1]
  1. State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012 (China)
Publication Date:
OSTI Identifier:
22486377
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM HYDRIDES; COMPRESSION; DENSITY; DIAMONDS; HYDROGEN STORAGE; LITHIUM HYDRIDES; MONOCLINIC LATTICES; PHASE TRANSFORMATIONS; PRESSURE RANGE MEGA PA 10-100; SPACE GROUPS; X-RAY DIFFRACTION