Prediction for high superconducting ternary hydrides below megabar pressure.

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 UHand UH. Our results indicate several compounds possess superconducting critical temperature () above liquid nitrogen temperature below 100 GPa, such as CeBeHand ThBeHthat are dynamical stable with aof 201 K at 30 GPa and aof 98 K at 10 GPa, respectively. Further formation enthalpy calculations suggest that thermodynamical stable pressure of CeBeHand ThBeHcompounds is above 50 GPa and 88 GPa with respect to binary compounds and solid elements. Moreover, we also found that ThBeHcould be dynamically stable down to 20 GPa with aof 70 K. Our further simulations suggested this newly predicted ThBeHis 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.