High-pressure phase transition of alkali metal-transition metal deuteride Li2PdD2

Yansun Yao; Elissaios Stavrou; Alexander F Goncharov; Arnab Majumdar; Hui Wang; Vitali B Prakapenka; Albert Epshteyn; Andrew P Purdy

doi:10.1063/1.4986245

High-pressure phase transition of alkali metal-transition metal deuteride Li₂PdD₂

J Chem Phys. 2017 Jun 21;146(23):234506. doi: 10.1063/1.4986245.

Authors

Yansun Yao¹, Elissaios Stavrou², Alexander F Goncharov², Arnab Majumdar¹, Hui Wang³, Vitali B Prakapenka⁴, Albert Epshteyn⁵, Andrew P Purdy⁵

Affiliations

¹ Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada.
² Geophysical Laboratory, Carnegie Institution of Washington, NW, Washington, DC 20015, USA.
³ State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China.
⁴ Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, USA.
⁵ Chemistry Division, Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, DC 20375, USA.

PMID: 28641439
DOI: 10.1063/1.4986245

Abstract

A combined theoretical and experimental study of lithium palladium deuteride (Li₂PdD₂) subjected to pressures up to 50 GPa reveals one structural phase transition near 10 GPa, detected by synchrotron powder x-ray diffraction, and metadynamics simulations. The ambient-pressure tetragonal phase of Li₂PdD₂ transforms into a monoclinic C2/m phase that is distinct from all known structures of alkali metal-transition metal hydrides/deuterides. The structure of the high-pressure phase was characterized using ab initio computational techniques and from refinement of the powder x-ray diffraction data. In the high-pressure phase, the PdD₂ complexes lose molecular integrity and are fused to extended [PdD₂]_∞ chains. The discovered phase transition and new structure are relevant to the possible hydrogen storage application of Li₂PdD₂ and alkali metal-transition metal hydrides in general.