Synthesis of Weaire–Phelan Barium Polyhydride

Miriam Pena Alvarez, Jack Binns, Miguel Martinez-Canales, Bartomeu Monserrat, Graeme J Ackland, Philip Dalladay-Simpson, Ross T Howie, Chris J Pickard, Eugene Gregoryanz

Research output: Contribution to journalLetterpeer-review


By combining pressures up to 50 GPa and temperatures of 1200 K, we synthesize the novel barium hydride, Ba8H46, stable down to 27 GPa. We use Raman spectroscopy, X-ray diffraction, and first-principles calculations to determine that this compound adopts a highly symmetric Pm3¯n structure with an unusual 534:1 hydrogen-to-barium ratio. This singular stoichiometry corresponds to the well-defined type-I clathrate geometry. This clathrate consists of a Weaire–Phelan hydrogen structure with the barium atoms forming a topologically close-packed phase. In particular, the structure is formed by H20 and H24 clathrate cages showing substantially weakened H–H interactions. Density functional theory (DFT) demonstrates that cubic Pm3¯n Ba8H46 requires dynamical effects to stabilize the H20 and H24 clathrate cages.
Original languageEnglish
Pages (from-to)4910-4916
Number of pages7
JournalThe Journal of Physical Chemistry Letters
Issue number20
Early online date19 May 2021
Publication statusPublished - 27 May 2021


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