High pressure study of sodium trihydride

Tomas Marqueno, Mikhail A. Kuzovnikov, Israel Osmond, Philip Dalladay-Simpson, Andreas Hermann, Ross T. Howie, Miriam Pena Alvarez*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The reactivity between NaH and H2 has been investigated through a series of high-temperature experiments up to pressures of 78 GPa in diamond anvil cells combined with first principles calculations. Powder X-ray diffraction measurements show that heating NaH in an excess of H2 to temperatures around 2000 K above 27 GPa yields sodium trihydride (NaH3), which adopts an orthorhombic structure (space group Cmcm). Raman spectroscopy measurements indicate that NaH3 hosts quasi-molecular hydrogen (Hδ−2) within a NaH lattice, with the Hδ−2 stretching mode downshifted compared to pure H2 (Δν ∼−120 cm−1 at 50 GPa). NaH3 is stable under room temperature compression to at least 78 GPa, and exhibits remarkable P-T stability, decomposing at pressures below 18 GPa. Contrary to previous experimental and theoretical studies, heating NaH (or NaH3) in excess H2 between 27 and 75 GPa does not promote further hydrogenation to form sodium polyhydrides other than NaH3.
Original languageEnglish
Article number1306495
Pages (from-to)1-8
Number of pages8
JournalFrontiers in chemistry
Volume11
DOIs
Publication statusPublished - 9 Jan 2024

Keywords / Materials (for Non-textual outputs)

  • hydrides
  • sodium
  • high pressure
  • X-ray diffraction
  • Raman
  • density functional calculations

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