Prediction for high superconducting ternary hydrides below megabar pressure

Abstract

Abstract The recent findings of high-temperature hydrides ushered a new era of superconductivity research under high pressure. However, the stable pressure for these remarkable hydrides remains extremely high. In this work, we performed the extensive simulations on a series of hydrides with the prototype structure of UH8 and UH7. Our results indicate several compounds possess superconducting critical temperature (T c) above liquid nitrogen temperature below 100 GPa, such as CeBeH8 and ThBeH8 that are dynamical stable with a T c of 201 K at 30 GPa and a T c of 98 K at 10 GPa, respectively. Further formation enthalpy calculations suggest that thermodynamical stable pressure of CeBeH8 and ThBeH8 compounds is above 50 GPa and 88 GPa with respect to binary compounds and solid elements. Moreover, we also found that ThBeH7 could be dynamically stable down to 20 GPa with a T c of 70 K. Our further simulations suggested this newly predicted ThBeH7 is thermodynamically stable above pressure of 33 GPa with respect to binary compounds and solid elements. The present results shed light on future design and discovery of high-temperature superconductor at moderate pressure.