Theoretical studies for stability, mechanical properties, electronic properties and Debye temperature of novel Cr 2 C structures

The stabilities, mechanical and electronic properties and Debye temperature of three novel Cr 2 C structures ( Pnnm , Amm 2 and P- 31 m space groups ) are investigated and discussed in this paper. All of them are thermodynamically, mechanically and dynamically stable. Notably, the hardness of Amm 2 Cr 2 C is 26.30 GPa at ambient pressure, better than the known Cr 2 C structures. Based on the results of the density of state and Mulliken overlap population simulation, there is strong covalent-ionic Cr-C bonding interaction in Amm 2 Cr 2 C, which is also revealed by the analysis of Debye temperature. Furthermore, the relative enthalpy as functional of pressure of all structures were calculated to understand their stabilities under high pressure. Overall, the predicted stable structures will provide more options to facility the synthesis and application of transition metal carbides.