Predicting superconductivity near 70 K in 1166-type boron-carbon clathrates at ambient pressure

The search for a novel superconductor exhibiting a high critical temperature (high T₂) or even near room temperature at an accessible synthetic pressure is a persistent objective for both experimental and theoretical physicists. Here, we conduct a systematic high-throughput structure search on boron-carbon clathrates at ambient pressure and uncover two stable 1166-type superconductors, RbYbB₆C₆ and RbBaB₆C₆, both exhibiting maximum T₂70 K. The high-T₂ superconductivity in 1166-type superconductors is attributed to two key factors: an enhanced density of states at the Fermi level and the strong B-C covalent framework in boron-carbon clathrates, which enhance the electron-phonon coupling and facilitate superconductivity at temperatures near the boiling point of liquid nitrogen. These results provide a significant advancement in understanding the underlying mechanisms of superconductivity in 1166-type boron-carbon based superconductors and offer valuable avenues for the design and synthesis of advanced high-temperature superconductors at ambient conditions.