Pressure-induced structural and electronic changes in α-Al H3

J. Graetz, S. Chaudhuri, Y. Lee, T. Vogt, James Muckerman, J. J. Reilly

Research output: Contribution to journalArticle

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Abstract

Pressure-induced structural, electronic, and thermodynamic changes in α-Al H3 were investigated using synchrotron x-ray powder diffraction and density-functional theory. No first-order structural transitions were observed up to 7 GPa. However, increasing Bragg peak asymmetry with pressure suggests a possible monoclinic distortion at moderate pressures (1-7 GPa). The pressure-volume relationship was fit to the Birch-Murnaghan equation of state to give a bulk modulus of approximately 40 GPa. The reduced cell volume at high pressure is accommodated by octahedral tilting and a decrease of the Al-H bond distance. Ab initio calculations of the free energy indicate that hydrogenation becomes favorable at H2 pressures above 0.7 GPa at 300 K. Electronic density of states calculations reveal a slight decrease in the band gap with pressure but no evidence of an insulator-to-metal transition predicted by previous high-pressure studies. Calculated Mulliken charges and bond populations suggest a mixed ionic and covalent Al-H bond at 1 atm with an increase in covalent character with pressure.

Original languageEnglish
Article number214114
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume74
Issue number21
DOIs
Publication statusPublished - 2006

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electronics
bulk modulus
Electronic density of states
hydrogenation
synchrotrons
equations of state
Synchrotrons
Equations of state
transition metals
free energy
asymmetry
insulators
Free energy
Hydrogenation
Transition metals
Density functional theory
density functional theory
Energy gap
thermodynamics
Elastic moduli

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Pressure-induced structural and electronic changes in α-Al H3. / Graetz, J.; Chaudhuri, S.; Lee, Y.; Vogt, T.; Muckerman, James; Reilly, J. J.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 74, No. 21, 214114, 2006.

Research output: Contribution to journalArticle

Graetz, J. ; Chaudhuri, S. ; Lee, Y. ; Vogt, T. ; Muckerman, James ; Reilly, J. J. / Pressure-induced structural and electronic changes in α-Al H3. In: Physical Review B - Condensed Matter and Materials Physics. 2006 ; Vol. 74, No. 21.
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