Sodalite-like carbon based superconductors with Tc about 77 K at ambient pressure

Abstract

The attainment of superconductivity at room temperature is a longstanding aspiration for both experimental and theoretical scientists. Materials exhibiting superconductivity under ambient conditions would have significant applications. Here, we report two metastable phases of sodalite-like carbon based superconductors, GaC₆ and GeC₆, at ambient pressure using the CALYPSO structural search method and first-principles calculations. Our calculations reveal that both GaC₆ and GeC₆ compounds have Imm symmetry and are dynamically stable at ambient pressure with T_c values up to the boiling point of liquid nitrogen. The underlying mechanisms indicate that the guest Ga and Ge atoms play a dual role in enhancing the structural stability and concurrently acting as electron donors, thereby modulating the electronic properties of the C₂₄ covalent frameworks, i.e. from insulating states to superconducting states. The present results offer insights into the exploration of novel high temperature superconductors under ambient conditions.