Cubic diamondlike BC7 predicted from first principles as a superhard material

A cubic diamondlike BC7 structure with I-43m space group and 64 atoms per cell is theoretically designed from first-principles calculations. Our calculated phonon spectra and elastic constants confirmed that BC7 is both dynamically and mechanically stable. Based on the calculated electronic band structure and density of states, a hole-conducting behavior is predicted in BC7. The simulated high elastic constants, modulus, hardness and ideal strength reveal that BC7 exhibits excellent mechanical characters and belongs to a superhard material with prospects for potential multi-functional material in electronic and mechanical application.