The Synthesis and Structural Characterization of Na3WO3N

Abstract We report the discovery of a new ternary oxynitride, Na 3 WO 3 N. Na 3 WO 3 N is synthesized by exposing a eutectic melt consisting of 1 2 Na 2 O : 1Na 2 WO 4 to a flow of ammonia gas at 695°C. The compound crystallizes in the acentric space group Pmn 2 1 with a = 7.2481(3) A, b = 6.2728(3) A, and c = 5.6493(2) A. The structure was determined from synchrotron X-ray powder diffraction data and refined using the Rietveld analysis on neutron powder diffraction data. It is isostructural to the low temperature form of Li 3 PO 4 which can be derived from an ordered wurtzite structure-type with all the atoms having tetrahedral coordination. Alternatively, the structure can be described as being "salt-like" consisting of isolated (WO 3 N) -3 tetrahedral polyanions separated by Na + .