Thermally stable luminescence and structure evolution of (K, Rb)BaPO4:Eu2+ solid-solution phosphors

The orthophosphate phosphors ABaPO(4):Eu2+ (A = K, Rb) have been studied in this paper. The continuous solid-solution phases in (K-X,Rb1-X)BaPO4 have been determined and the phase structure evolution and its dependence on the K: Rb ratio have been discussed, and all the Eu2+-doped (K-X,Rb1-x)BaPO4 phosphors show a blue emission, peaking at approximately 420 nm, originating from the 4f-5d transition of Eu2+. The differences in the fine microstructure have been investigated and the effect on the photoluminescence behavior, especially the thermally stable luminescence, has been studied for this series of solid-solution phosphors. The relationship between the activation energy and thermally stable luminescence is also discussed. The compositionally optimized (K-X,Rb1-X)BaPO4:Eu2+ phosphor can be potentially applied in phosphor-converted white light-emitting diodes (w-LEDs).