Structure and light emission of scheelite-type ACe(WO4)2 (A = Li, Na, or K)

In this study, KCe(WO4)2 was synthesized by a solid-state reaction of K2CO3, CeO2, and WO3 at 1273 K for 12 h. The Rietveld refinement of this sample confirmed the scheelite-type (tetragonal) structure for KCe(WO4)2, with a I41/a space group and lattice parameters a = 542.4 pm and c = 1207 pm. The lattice parameters for ACe(WO4)2 (A = Li, Na, or K) were in agreement with the ionic radii of the alkali metal ions, but the W–O distance in KCe(WO4)2 was found to be shorter than those in the other compounds, indicative of the distortion of WO42–, attributed to the larger ionic radius of K+. All of the synthesized ACe(WO4)2 materials exhibited fluorescence, with the relative emission intensity decreasing in the order of KCe(WO4)2 > NaCe(WO4)2 > LiCe(WO4)2.