Theoretical prediction of high-temperature superconductivity above 80 K in boron carbide at ambient pressure

The pursuit of room-temperature superconductors remains a critical challenge in modern science. Here, we perform comprehensive high-throughput structure searches for boron carbide (BC) at ambient pressure using CALYPSO method and first-principles calculations. The structure searches rapidly identify the ground state and two new stable phases,P6₃mcandPmm2, of BC compounds at ambient pressure. TheP6₃mcphase shows remarkable superconductivity with high superconducting transition temperature (T_c) up to 86 K, exceeding the boiling point of liquid nitrogen. Our calculations indicate that the highT_cvalue of theP6₃mcphase of BC arises from its metallizedσ-bands and dominant hole-like pockets crossing the Fermi level. Moreover, thePmm2 phase of BC compound is verified as a superhard superconductor, withT_cof 24 K and Vickers hardness of 44 GPa. These theoretical findings not only enrich the understanding of potential ambient superconductors but also offer promising avenues for the design and synthesis of advanced high-temperature superconductors at ambient pressure.