Diffusion-driven transient hydrogenation in metal superhydrides at extreme conditions

Yishan Zhou, Yunhua Fu, Meng Yang, Israel Osmond, Rajesh Jana, Takeshi Nakagawa, Owen Moulding, Jonathan Buhot, Sven Friedemann, Dominique Laniel, Thomas Meier*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

In recent years, metal hydride research has become one of the driving forces of the high-pressure community, as it is believed to hold the key to superconductivity close to ambient temperature. While numerous novel metal hydride compounds have been reported and extensively investigated for their superconducting properties, little attention has been focused on the atomic and electronic states of hydrogen, the main ingredient in these novel compounds. Here, we present combined 1H- and 139La-NMR data on lanthanum superhydrides, LaH x, (x = 10.2 - 11.1), synthesized after laser heating at pressures above 160 GPa. Strikingly, we found hydrogen to be in a highly diffusive state at room temperature, with diffusion coefficients in the order of 10 -6cm 2s -1. We found that this diffusive state of hydrogen results in a dynamic de-hydrogenation of the sample over the course of several weeks, approaching a composition similar to its precursor materials. Quantitative measurements demonstrate that the synthesized superhydrides continuously decompose over time. Transport measurements underline this conclusion as superconducting critical temperatures were found to decrease significantly over time as well. This observation sheds new light on formerly unanswered questions on the long-term stability of metal superhydrides.

Original languageEnglish
Article number1135
Pages (from-to)1-8
Number of pages8
JournalNature Communications
Volume16
Issue number1
DOIs
Publication statusPublished - 29 Jan 2025

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