High-pressure phase transition observed in barium hydride

  1. Get@NRC: High-pressure phase transition observed in barium hydride (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1063/1.2772427
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Journal titleJournal Of Applied Physics
Pages0435208; # of pages: 43513
Subjectab initio calculations; barium compounds; crystallisation; elastic moduli; high-pressure solid-state phase transformations; Raman spectra; vibrations; X-ray diffraction
AbstractThe pressure-dependent structural and vibrational properties of barium hydride have been studied up to 22 GPa at room temperature by means of powder x-ray diffraction, Raman spectroscopy, and first-principles calculations. At ambient conditions, BaH2 crystallizes in the cotunnite structure (Pnma). A reversible, first-order structural phase transition is observed at 1.6 GPa. The high-pressure phase can be indexed by a hexagonal unit cell with a proposed Ni2In structure (P63/mmc), with the Ba and H atoms in special positions. The experimental volume compression of the high-pressure phase yields an isothermal bulk modulus B0=24(1) GPa (B<sub>0</sub><sup>[prime]</sup> fixed at 4.13). This compares favorably with the results of the first-principles calculations, which reproduce the first-order nature of the transition. The relevance of these results is discussed in the contexts of metal hydrides in particular and ionic AX2 (A=metal) compounds in general.
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AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
NPARC number12338985
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Record identifier5fed8edf-817b-4f16-9a62-326970bbb4c0
Record created2009-09-11
Record modified2016-05-09
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