Superconductivity in CeBeH₈and CeBH₈at moderate pressures

High-pressure structural searches of superhydrides CeBeH₈and CeBH₈were performed under ambient pressure up to 300 GPa. We identifyFm3‾m-CeBeH₈with a superconducting transition temperatureTof 56 K at 10 GPa. Two more phases with spacegroupR3‾mandC2/m, were investigated within the increasing pressures. CeBH₈shows a similar phase transition process as CeBeH₈but with higher transition pressures and higherT.Fm3‾m-CeBH₈is predicted to be superconducting above 120 GPa with a maximumTof 118 K at 150 GPa.R3‾m-CeBH₈andC2/m-CeBH₈are dynamically stable above 120 GPa and 100 GPa, respectively. The maximumTis 123 K at 195 GPa forR3‾m-CeBH₈, and 115 K at 350 GPa forC2/m-CeBH₈. Our work enriches the family of ternary hydrides and may provide a useful guideline for further search for superconducting hydrides at low and moderate pressures.