Search for high-pressure ternary superhydrides in the Pb-Li-H and Cu-Li-H systems.

Superhydrides form a novel class of compounds obtained through the significant uptake of hydrogen by a metal under high hydrogen pressure, with great potential for hydrogen storage and high-temperature superconductivity. However, none has yet been recovered at ambient pressure. The search for such recoverable superhydrides is now focusing on ternary hydrides. The goal of this proposal is to explore the Cu-Li-H and Pb-Li-H systems. Lithium should aid electrons transfer and favor the formation of superhydrides when combined to Pb or Cu. In particular, Li₂CuH₆ has been recently predicted to be a recoverable metastable compound at ambient pressure with a Tc around 80 K. The hydriding of Li-Pb compounds is also of great importance in view of the widespread use of Li-Pb compounds as coolants and tritium breeders in nuclear fusion reactors. X-ray diffraction (XRD) will be crucial for identifying any new compounds, and DFT calculations will then be performed to obtain the hydrogen positions.