High-temperature superconductivity in quinary clathrate hydrides under pressure

The search for high-temperature superconductivity among pressure-stabilized hydrides has received great interest since theory-directed clathrate hydrides, such as CaH₆, YH₆, YH₉, and LaH₁₀, were synthesized and shown to exhibit a superconducting critical temperature (Tc) above 200 K. However, further tuning the superconductivity and stability of these prominent hydrides to enhance their applicability remains a significant challenge. Here, taking the sodalitelike clathrate prototype MH₆ (M=Ca, Y, etc.) as an example, we investigate the stability and superconductivity of multicomponent metal hydrides containing four different metal atoms per structure. High-throughput simulations of 1820 ABCDH₂₄ quinary hydrides, with initial symmetry of F4̄3m and varying metal atoms ($A, B, C$, and D), were conducted. The results identified 119 dynamically stable structures at 300 GPa, with 67 exhibiting superconductivity exceeding 200 K, and 20 having Tc values above 260 K. Notably, (Na,Zr,Mg,Hf)H₆ is predicted to approach room temperature Tc at 250 GPa. Both configurational and vibrational entropy are crucial for stabilizing these alloys. (Na,Y,Zr,Hf)H₆, (Mg,Zr,Sc,Y)H₆, and (Mg,Hf,Ca,Zr)H₆ were computed to be thermodynamically stable, making them promising candidates for experimental synthesis. These quinary superconducting hydrides may facilitate the realization of very high-temperature superconductors being stable over a broader range of conditions than binary or ternary systems.