Effects of charge compensation on the luminescence behavior of Eu3+ activated CaWO4 phosphor

A series of red-emitting phosphors containing Ca1−xEuxWO4+0.5x, Ca1−1.5xEuxWO4 and Ca1−2xEuxMxWO4 (x = 0.24, M = Li, Na, K) were prepared by conventional solid state reactions. All of the phosphors can be effectively excited by 395 and 465 nm light, and exhibit superior red emission around 615 nm to the commercial red phosphor Y2O2S:Eu3+. In Ca1−xEuxWO4+0.5x, one Ca2+ ion was replaced by one Eu3+ without direct charge compensation. Whereas in Ca1−1.5xEuxWO4 and Ca1−2xEuxMxWO4 phosphors, the charge was compensated by two Eu3+ ions substituting for three Ca2+ ions, or one Eu3+ and one M+ ion replacing two Ca2+ ions, respectively. The evident enhanced emissions were observed in Ca1−1.5xEuxWO4 and Ca1−2xEuxMxWO4 (x = 0.24, M = Li, Na, K) phosphors, which implies that efficient charge compensation can promote the luminescence of Eu3+ in CaWO4.