DEFECTIVE AND AMORPHOUS STRUCTURE OF CARBON NITRIDE

There has been enormous interest in preparing the superhard material C 3N4, With the large nitrogen concentration being one factor limiting p reparation. Using an ab initio supercell approach we simulate the elec tronic structure about a N vacancy and investigate the effect it has o n the bulk modulus of the material. We compare this with a relaxed cub ic C3N3 structure with one N atom removed. The ability of the superlat tice to model the electronic structure of the crystalline material is used to deduce properties of an amorphous structure within the ab init io framework. The amorphous form has a bulk modulus significantly lowe r than its crystalline counterpart and comparison of various structure s suggests that the final strength of carbon nitride will ultimately d epend upon the number of C-N bonds that can be formed during synthesis of the material.