摘要：We have analyzed the compositions of boron–carbon system, in which the $$\hbox {BC}_{{7}}$$ 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 $$\hbox {BC}_{{7}}$$ . Our results have demonstrated that the $$\hbox {BC}_{{7}}$$ is thermodynamically stable in the diamond-like $$P{\bar{4}}m2$$ 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 $$P{\bar{4}}m2$$ 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 $$P{\bar{4}}m2$$ phase can achieve a high superconducting transition temperature ( $$\hbox {T}_{{c}}$$ ). The outstanding property of $$\hbox {BC}_{{7}}$$ at 250 GPa has manifested very high- $$\hbox {T}_{{c}}$$ of superconductivity as 164 K, indicating that the carbon-rich system can induce the high- $$\hbox {T}_{{c}}$$ value as well.
其他摘要：Abstract We have analyzed the compositions of boron–carbon system, in which the $$\hbox {BC}_{{7}}$$ BC 7 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 $$\hbox {BC}_{{7}}$$ BC 7 . Our results have demonstrated that the $$\hbox {BC}_{{7}}$$ BC 7 is thermodynamically stable in the diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 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 $$P{\bar{4}}m2$$ P 4 ¯ m 2 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 $$P{\bar{4}}m2$$ P 4 ¯ m 2 phase can achieve a high superconducting transition temperature ( $$\hbox {T}_{{c}}$$ T c ). The outstanding property of $$\hbox {BC}_{{7}}$$ BC 7 at 250 GPa has manifested very high- $$\hbox {T}_{{c}}$$ T c of superconductivity as 164 K, indicating that the carbon-rich system can induce the high- $$\hbox {T}_{{c}}$$ T c value as well.
