Pressure-induced solubility suppression for boron–carbon–nitride ternary alloys

Pressure effects on phase stability of boron–carbon–nitride (BCN) ternary alloys in diamond- and wurtzite-like structures are quantitatively examined based on first-principle calculations. We find that external pressure increases solution enthalpy of neighboring B–N or C–C pair into carbon or boron–nitride (BN), which leads to decrease in solubility. The increase in solution enthalpy can be mainly attributed to increase in volume upon forming solid solution between carbon and BN: forming of neighboring B–C, C–N, B–B, or N–N pair causes increase in volume with respect to B–N and C–C pairs. The increase in volume occurs in whole composition, which is confirmed by combination of first-principle calculation and cluster expansion technique.