High-pressure synthesis and study of low-compressibility molybdenum nitride (MoN and MoN_1−x) phases

We report the compressibility of the stoichiometric hexagonal δ phase of MoN that is a well-known hard material that becomes superconducting below T_c = 12 K. The measured bulk modulus is K₀ = 345(9) GPa and K₀^′=3.5(3). We also report the compressibility of the non-stoichiometric cubic B1 structured γ − Mo₂N phase, that has a lower bulk modulus [K₀ = 301(7) GPa, assuming K₀^′=4]. The difference in bulk modulus is due to the difference in structure and the cohesive energy between the two phases.