Optimized photoluminescence by charge compensation in a novel phosphor system

A series of red phosphors, Ca0.54Sr0.22Eu0.08La0.08 (MoO4)x(WO4)1−x with charge compensation, were synthesized by solid-state reaction. Three approaches to achieve charge compensation are tried: (a) 2Sr2+→Eu3+/La3++M+, where M+ is a monovalent cation like Li+, Na+ or K+ acting as charge compensator; (b) charge compensation is provided by calcium vacancy, 3Sr2+→2Eu3+/La3++vacancy; (c) Sr2+→Eu3+/La3++N−, where N− is a monovalent anion like Cl−. Charge compensation is a good way in obtaining potential red-emitting candidates for the white LED. These phosphors can be efficiently excited by 394, 465 and 535 nm, which are suitable with the emission of n-UV LED and blue LED.