Crystal structures and luminescence properties of Li6 MN4:Ce3+ (M = Mo, W)

Abstract

Abstract The compounds Li6MoN4 and Li6WN4 were prepared from the reactants M (M = Mo, W) and Li3N in a radiofrequency furnace at 1000 °C. The lithonitridometallates crystallize in the tetragonal system with the lattice parameters: a = 6.6844(1), c = 4.9294(1) Å for Li6WN4 based on single-crystal X-ray diffraction data and a = 6.6611(3), c = 4.9338(3) Å for Li6MoN4 taken from powder X-ray diffraction data. Colorless to slightly reddish single-crystals of the tungsten compound were isolated and the crystal structure was refined in the space group P42/nmc (no. 137) with Z = 2 and the powder X-ray data of the molybdenum compound were analyzed by a Rietveld refinement. Both structures belong to the Li6[ZnO4] type published by Hoppe et al. in 1987 (Untenecker H., Hoppe R. Z. Anorg. Allg. Chem. 1987, 551, 147–150) and could be doped with Ce3+ for the first time. The investigated compounds show a reddish color impression upon UV to blue irradiation and exhibit a broad emission band with a maximum at λ max = 693 nm (fwhm 97 nm) for Li6MoN4 and at λ max = 653 nm (fwhm 133 nm) for Li6WN4.