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

Abstract

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 WO₄^2–, 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.