Route to high‐Tc superconductivity of BC7 via strong bonding of boron–carbon compound at high pressure

Abstract

We have analyzed the compositions of boron–carbon system, in which the BC7 compound is identified as structural stability at high pressure. The first-principles calculation is used to identify the phase diagram, electronic structure, and superconductivity of BC7. Our results have demonstrated that the BC7 is thermodynamically stable in the diamond-like P4¯m2 structure at a pressure above 244 GPa, and under temperature also. Feature of chemical bonds between B and C atoms is presented using the electron localization function. The strong chemical bonds in diamond-like P4¯m2 structure are covalent bonds, and it exhibits the s–p hybridization under the pressure compression. The Fermi surface shape displays the large sheet, indicating that the diamond-like P4¯m2 phase can achieve a high superconducting transition temperature (Tc). The outstanding property of BC7 at 250 GPa has manifested very high-Tc of superconductivity as 164 K, indicating that the carbon-rich system can induce the high-Tc value as well.