Synthesis and superconductivity in (La,Ca)H10 under high pressure

Abstract

Tracking room-temperature superconductors represents a significant challenge and opportunity, while the discovery of binary lanthanum hydrides provides a crucial platform for exploring ternary hydrides with exceptional properties. The theoretically studied La-Ca-H system is also one of the attractive candidates for room-temperature superconductivity. In this work, we have successfully synthesized two La-Ca hydrides by doping Ca elements into the La-H system. The temperature dependence of the electrical resistance demonstrates the superconductivity of Fm3¯m−(La,Ca)H10 and P63/mmc−(La,Ca)H10, with superconducting critical temperature (Tc) of 247 K (173 GPa) and 230 K (167 GPa), respectively. Present results show that doping with 10% or 15% Ca has only a negligible effect on the Tc of LaH10, which is consistent with Anderson's theory. Although the high Tc phase of La-Ca-H maintains a highly symmetric fcc structure, the doping of Ca may lead to premature H-cage distortion during the decompression process, thus affecting the structural stability of the system. Therefore, under the doping levels and synthesis conditions of this work, we think that Ca may not be an ideal dopant. Our study provides some hints on the key factors affecting superconductivity and informs the future search for room-temperature superconductors in more diverse hydride materials.

Source-reported materials — not catalogue approval

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