Theoretical research on novel orthorhombic tungsten dinitride from first principles calculations

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 WN_0.6 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 (P6) having lattice parameters of a = 8.2398(3) Å, c = 2.94948(14) Å, and V = 173.423(13) ų. Tungsten atoms are coordinated to eight and nine nitrogen atoms, higher than previously reported tungsten nitrides. The bulk modulus is determined to be K₀ = 312 (5) GPa (K₀^' = 4.0 fixed), and DFT calculations predict that U₇Te₁₂-type W₇N₁₂ has a metallic nature.