Recent computational studies have successfully predicted the dramatic uptake of hydrogen by metals under pressure leading to the formation of superhydrides, now ubiquitously observed. ${\mathrm{LaH}}_{10}$ exemplifies the properties of these novel H-rich compounds, some of which form a novel class of superconducting materials. We show here another remarkable property for superhydrides, namely, ${\text{H}}^{\delta -}$ superionicity. By means of ab initio molecular dynamics simulations in ${\mathrm{LaH}}_{10}$, an exceptionally high hydride $\left({\mathrm{H}}^{\delta -}\right)$ diffusion coefficient is calculated at high temperature, with $D=1.7\times {10}^{-4}\mathrm{cm} {}^2$/s at 170 GPa and 1500 K, corresponding to an ionic conductivity of $\sigma =0.9{\left(\mathrm{\Omega }\mathrm{cm}\right)}^{-1}$ and so indicating a superionic phase. The superionic phase is surprisingly stable up to 2500 K and its melting temperature is remarkably high, similar to that of pure La. The connected path for the hydride ionic diffusion is disclosed, with the H sublattice keeping its clathrate structure. The conductivity properties of ${\mathrm{LaH}}_{10}$ are discussed in relation to the recently discovered family of compounds showing fast pure hydride ions transport.

Close

PrevNext

View figure in article

• Diffusion
• First-principles calculations
• Hydrogen storage
• Ionic transport
• Pressure effects
• Hydrides
• Ab initio molecular dynamics