Valence electron structure analysis of intrinsic hardness for diamond and c-BN

Based on the Pauling's nature of chemical bond, the valence electron structures of diamond and c-BN crystals have been constructed. Then the relationship between covalent bond and glide plane system is analyzed. The results show that the hardness of diamond and c-BN is correlated to the covalent electron structure and the slip system of crystals. The hardness for diamond and c-BN so large is explained satisfactory form valence electron structures.