High-pressure phases and pressure-induced phase transition of MoN6 and ReN6

Transition metal nitrides have been widely used in many scientific and technical areas because of their unique physical and mechanical properties. We report two new nitrogen-rich transition metal nitrides, MoN6 and ReN6, by crystal structure searching technique. Under high pressure, MoN6 will undergo phase transition (from R-3m to Pm-3 phase) at 54 GPa, and ReN6 always keep the R-3m phase in the pressure range from 50 to 100 GPa. There are benzene-like six-membered N6 rings with nitrogen single bonds in the R-3m phase structures, indicating that MoN6 and ReN6 are expected to be the high-energy-density materials. (C) 2019 Elsevier B.V. All rights reserved.