Structural forms of cubicBC2N

Superhard cubic boron-carbonitrides $(c-{\mathrm{BC}}_2\mathrm{N})$ are studied with the use of the ab initio pseudopotential density functional method. The total energy, lattice constant, bulk and shear moduli, and electronic band structures as well as the electron density of states are calculated for all the possible $c-{\mathrm{BC}}_2\mathrm{N}$ structures in an eight-atom zinc-blende-structured cubic unit cell. The results obtained provide a plausible explanation for recent experimental observations as well as a possible path to synthesis of the materials.