Ternary superconducting hydrides in the La-Mg-H system

Abstract

Ternary or more complex hydrogen-rich hydrides are the main hope of reaching room-temperature superconductivity at high pressures. Their chemical space is vast and its exploration is challenging. Here we report the investigation of the La-Mg-H ternary system using the evolutionary algorithm USPEX at pressures on the range 150-300 GPa. Several ternary superconducting hydrides were found, including thermodynamically stable $P6/mmm$-LaMg${}_3$H${}_{28}$ with $T_{\mathrm{C}}=164$ K at 200 GPa, $P/2m$-LaMgH${}_8$, $C2/m$-La${}_2$MgH${}_{12}$ and $P2/m$-La${}_3$MgH${}_{16}$. In addition, novel binary hydrides were predicted to be stable at various pressures, such as $Cm$-Mg${}_6$H${}_{11}$, $P1$-MgH${}_{26}$, $Fmm2$-MgH${}_{30}$, $P1$-MgH${}_{38}$ and $R\overline{3}m$-LaH${}_{13}$. We also report several novel low-enthalpy metastable phases, both ternary and binary ones. Finally, we demonstrate important methods of exploring very large chemical spaces and show how they can improve crystal structure prediction.

References in corpus (3)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Prediction of high-Tc superconductivity in ternary lanthanum borohydrides
• High-Pressure Synthesis of Seven Lanthanum Hydrides with a Significant Variability of Hydrogen Content

Cited by in corpus (3)

• Large negative magnetoresistance and pseudogap phase in superconducting A15-type La${}_4$H${}_{23}$
• Superconductivity in barium hydrides via incorporation of light elements
• Superconducting ternary compounds Li-X-B (X=Mo, W) within the mild pressure range: First-principles predictions