Crystal And Electronic Structure Of U7te12-Type Tungsten Nitride Synthesized Under High Pressure

Tungsten nitride continues to drive fundamental interests because of its potential as a functional compound, which combines features such as high hardness together with thermal, chemical, and wear resistance. Here, we report a novel tungsten nitride phase synthesized from MoC-type WN0.6 and molecular nitrogen after laser irradiation at P = 70 GPa in a diamond anvil cell. This novel phase is quenchable at ambient pressure and determined to be U7Te12-type tungsten nitride and crystallizes in the hexagonal space group (P (6) over bar) having lattice parameters of a = 8.2398(3) angstrom, c = 2.94948(14) angstrom, and V = 173.423(13) angstrom(3). Tungsten atoms are coordinated to eight and nine nitrogen atoms, higher than previously reported tungsten nitrides. The bulk modulus is determined to be K-0 = 312 (5) GPa (K-0' = 4.0 fixed), and DFT calculations predict that U7Te12-type W7N12 has a metallic nature.