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High-Pressure Synthesis and Characterization of Iridium Trihydride

DOI: 10.1103/PhysRevLett.111.215503 DOI Help
PMID: 24313503 PMID Help

Authors: Thomas Scheler (University of Edinburgh) , Miriam Marqués (Universidad de Oviedo) , Zuzana Konôpková (DESY Photon Science) , Christophe L. Guillaume (School of Physics and Centre for Science at Extreme Conditions, The University of Edinburgh) , Ross T. Howie (University of Edinburgh) , Eugene Gregoryanz (School of Physics and Centre for Science at Extreme Conditions, The University of Edinburgh)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Letters , VOL 111 (21)

State: Published (Approved)
Published: November 2013

Abstract: We have performed in situ synchrotron x-ray diffraction studies of the iridium-hydrogen system up to 125 GPa. At 55 GPa, a phase transition in the metal lattice from the fcc to a distorted simple cubic phase is observed. The new phase is characterized by a drastically increased volume per metal atom, indicating the formation of a metal hydride, and substantially decreased bulk modulus of 190 GPa (383 GPa for pure Ir). Ab initio calculations show that the hydrogen atoms occupy the face-centered positions in the metal matrix, making this the first known noninterstitial noble metal hydride and, with a stoichiometry of IrH3, the one with the highest volumetric hydrogen content. Computations also reveal that several energetically competing phases exist, which can all be seen as having distorted simple cubic lattices. Slow kinetics during decomposition at pressures as low as 6 GPa suggest that this material is metastable at ambient pressure and low temperatures.

Journal Keywords: Hydride

Subject Areas: Physics, Materials, Chemistry

Instruments: I15-Extreme Conditions

Other Facilities: ESRF; PETRAIII

Added On: 24/03/2014 10:24

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