Improving T_c in sodalite-like boron-nitrogen compound M₂(BN)₆

To explore the improvement of the critical temperature (T_c) of boron-nitrogen materials, the doping effect of other elements into the sodalite-like clathrate compounds M₂(BN)₆ is studied, based on the first-principles calculations. The stability, electronic structures, dynamical properties, and electron-phonon coupling interactions of these materials upon doping suggest that they are potential high-temperature superconductors. The result shows that the highest T_c of boron-nitrogen clathrate compound at ambient pressure reaches 72 K by doping Al. Boron-nitrogen clathrates doped by H, In, Tl, Si, and Ge also possess the high T_c values of 45, 54, 67, 58, and 41 K at ambient pressure, respectively. By increasing the doping concentration, the T_c value of boron-nitrogen clathrate can be obviously improved and nearly doubled. The predicted T_c of 72 K is the highest value for all boron-nitrogen materials at ambient pressure. It is much higher than those of magnesium diboride and alkali fullerides.