Synthesis and luminescence properties of ZnMoO4:Eu3+,M+(M+ = Li+, Na+ and K+)phosphors

Abstract

Zn1−1.5x MoO4:xEu3+ (x = 0.05, 0.10, 0.15, 0.20, 0.25) and Zn0.75MoO4:0.15Eu3+,0.05M+ (M+ = Li+, Na+, K+) phosphors were synthesized by the conventional solid state method in air. The XRD patterns of the phosphors indicate that the Eu3+ and M+ ions have successfully been introduced into the lattice. The luminescence intensity of ZnMoO4:Eu3+ phosphor decreases when the concentration of Eu3+ exceeds x = 0.15, the optimum dopant ion concentration. The charge compensator ions Li+, Na+, and K+ can improve the emission intensity of the ZnMoO4:Eu3+ phosphor with excitation at 394 nm and that of the Li+-doped system is greatest. The observed lifetimes for Eu3+ emission at 614 nm are 2.15, 3.46, 2.70 and 0.91 μs in ZnMoO4:Eu3+ and ZnMoO4:Eu3+,M+ (M = Li, Na, K), respectively. Hence, the Li+ co-doped ZnMoO4:Eu3+ phosphor has the longest lifetime. Under 394 nm excitation, the CIE coordinates of ZnMoO4:Eu3+,Li+ and ZnMoO4:Eu3+,Na+ are closer to those of ideal red light (0.67, 0.33) than those of commercial Y2O3:Eu3+ (0.625, 0.338). These experimental results are helpful in developing novel and high-efficiency red phosphors for white light-emitting diodes.