Highly Coordinated Tungsten Nitride with U₇Te₁₂-type Structure Synthesized Using the Laser-Heated Diamond Anvil Cell

Tungsten nitride (WN) has gained growing interest because of its potential as a functional compound. In our experiment, a novel WN was found when compressing and heating MoC-type WN using Laser-Heated Diamond Anvil Cell at a pressure of 70 GPa. Unknown peaks, different than those of the starting sample, were found in the XRD pattern. The unknown peaks were indexed using DICVOL calculation. By comparing the model structures base on the lattice parameters, space group, and EDS results, these unknown peaks were assigned to U₇Te₁₂-type W₇N₁₂. Rietveld refinement confirmed that this new structure has lattice parameters of a = 8.2398(3) Å, c = 2.94948(14) Å, and unit cell volume of V = 173.423 (13) ų. DFT calculations predicted that U₇Te₁₂-type W₇N₁₂ has a metallic behavior. This compound is the third example of a U₇Te₁₂-type structure ever found. The high nitrogen-coordinated tungsten polyhedra with coordination numbers of 8 and 9 has never been reported for other nitrides synthesized. Finally, this finding of a novel tungsten nitride compound confirms the feasibility of high-pressure synthesis techniques for the nitridation of tungsten. Moreover, it opens new possibilities and potentials in the W-N system that still need to be explored.