NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)solid solution red phosphors:Microstructure variation and luminescence enhancement induced by Zn^(2+)-doping

Red phosphor is an important component of the phosphor-converted white light-emitting diodes(pcWLEDs).The development of the novel red phosphor with excellent luminescence properties is of great significance for high performance WLEDs.In this study,NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)red phosphors with excellent luminescence properties were successfully synthesized and systematically investigated.Our results show that the Zn^(2+)-doping concentration has significant effect on the microstructures and luminescence properties of the NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)phosphors.The NaGd_(0.4)Eu_(0.6)Mg_(1-x)ZnxWO_(6)(0≤x≤0.7)samples are well crystallized pure solid solution sub-microcrystals,whereas the phase purity gradually decreases at 0.7<x≤1.0.The NaGd_(0.4)Eu_(0.6)Mg_(1-x)ZnxWO_(6)(0<x≤0.5)phosphors have stronger emissions than NaGd_(0.4)Eu_(0.6)MgWO_(6),and the optimized NaGd_(0.4)Eu_(0.6)Mg_(0.9)Zn_(0.1)WO_(6)phosphor possesses the best luminescence properties including thermal stability,CIE chromaticity coordinate,life time and quantum yield.The packaged WLED using NaGd_(0.4)Eu_(0.6)Mg_(0.9)Zn_(0.1)WO_(6)phosphor emits bright white light with higher CRI,lower CCT,and chromaticity coordinate close to the pure white light.The developed NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)phosphors have potential application in lighting and display.This work can offer an effective strategy for boosting luminescence properties of tungstate phosphors with the double perovskite structure.