Synthesis and Characterization of a New Ternary Transition Metal Nitride, FeWN2, from the Transition Metal Oxide Precursor, FeWO4

The ternary nitride, FeWN2, has been synthesized via ammonolysis of the transition metal tungstate, FeWO4. FeWN2 is hexagonal with a unit cell of a = 2.8724(1) Å and c =10.973(4) A. Rietveld refinements were performed in the space group P3–1C with Rwp=9.91%, and Rp=7.23%. The structure consist of alternating octahedrally coordinated iron-nitrogen layers and trigonal prismatically coordinated tungsten-nitrogen layers. Mössbauer data at 250K indicates an isomer shift δ=0.85 and shows no quadrupole splitting, which is consistent with the octahedral iron coordination in the proposed structure.