Ab initio study of the phase stability and mechanical properties of 5d transition metal nitrides MN2

Recently platinum nitride and some other heavy transition metal nitrides have attracted great interest due to their remarkable properties. However, there are many discrepancies in the reported results. In this work, we have systematically studied the phase stability, mechanical properties and chemical bonding characters of the heavy transition metal nitrides MN2 (M = Hf, Ta, W, Re, Os, Ir and Pt) in the pyrite and fluorite structures by ab initio methods. The present results will not only provide a fundamental understanding on these technologically important materials, but also benefit their practical applications.