Superhard solid solutions of diamond and cubic boron nitride

Single-phase BC4N can be formed at high pressure and temperature, starting with either a mixture of diamond and cubic boron nitride or graphite and hexagonal boron nitride. The samples exhibit extreme Vickers hardness (85 ± 4 GPa), reaching the hardness of single crystal diamond. Within a random solid solution model, the X-ray diffraction patterns of cubic BCxN solid solutions were calculated. The results indicate that the prepared B–C–N materials are continuous solid solutions with a zinc-blende structure.