First-principles study on hardness of five polymorphs of C3N4

摘要

Based on a new hardness model proposed by Simunek et al., the hardness of five polymorphs of C3N4 are investigated. Their hardness are more than 30 GPa which means that they are all good superhard materials. However, all these polymorphs are not harder than diamond. Comparing our results with the hardness calculated by Gao's hardness model, we find that the hardness obtained from the two hardness models are consistent in the case of five C3N4 polymorphs. (c) 2007 Elsevier B.V. All rights reserved.