Conventional hard and superhard materials,such as diamond and cubic boron nitride,are attractive for both scientific and industrial applications,but their intrinsically poor electrical conductivity limits broader use....Conventional hard and superhard materials,such as diamond and cubic boron nitride,are attractive for both scientific and industrial applications,but their intrinsically poor electrical conductivity limits broader use.This motivates the exploration of novel materials that combine superior hardness with excellent superconductivity.Herein,we performed a comprehensive structure search of the B–C system under pressures ranging from 0 to 100 GPa using machine-learning-potential(attention-coupled neural network,ACNN)based crystal structure prediction(CALYPSO).A stable BC 19 phase was identified at 50 GPa,featuring a diamond-like covalent framework with metallic character.Interestingly,BC 19 shows anisotropic superconductivity with an estimated superconducting critical temperature(T c)of 24 K at ambient pressure.Further analysis indicates that the high superconductivity of BC 19 originates from the strong coupling between theσelectrons and stretching vibrations of the covalent B–C framework.Additionally,BC 19 demonstrates superhard characteristics with a Vickers hardness of 76 GPa,exceeding that of cubic boron nitride.These results suggest that pressure-stabilized BC 19 represents a promising theoretical candidate for concurrent superconductivity and ultrahard mechanical performance.展开更多
基金supported by the National Key Research and Devel-opment Program of China(Grant Nos.2023YFA1406002 and 2023YFA1608901)the National Natural Science Foundation of China(Grant Nos.52288102,52090024,12374009,and T2495231)the Fundamental Research Funds for the Central Universities(Grant No.G1323525012).
文摘Conventional hard and superhard materials,such as diamond and cubic boron nitride,are attractive for both scientific and industrial applications,but their intrinsically poor electrical conductivity limits broader use.This motivates the exploration of novel materials that combine superior hardness with excellent superconductivity.Herein,we performed a comprehensive structure search of the B–C system under pressures ranging from 0 to 100 GPa using machine-learning-potential(attention-coupled neural network,ACNN)based crystal structure prediction(CALYPSO).A stable BC 19 phase was identified at 50 GPa,featuring a diamond-like covalent framework with metallic character.Interestingly,BC 19 shows anisotropic superconductivity with an estimated superconducting critical temperature(T c)of 24 K at ambient pressure.Further analysis indicates that the high superconductivity of BC 19 originates from the strong coupling between theσelectrons and stretching vibrations of the covalent B–C framework.Additionally,BC 19 demonstrates superhard characteristics with a Vickers hardness of 76 GPa,exceeding that of cubic boron nitride.These results suggest that pressure-stabilized BC 19 represents a promising theoretical candidate for concurrent superconductivity and ultrahard mechanical performance.
