Synthesis of scheelite structural Yb3+, Er3+ co-doped NaLa(MoO4)2 and its green upconversion luminescence

Abstract

The polycrystalline Er3+/Yb3+ co-doped NaLa(MoO4)2 phosphor was synthesized, and its green upconversion (UC) luminescence properties were investigated in detail. Under 980-nm excitation, Er3+/Yb3+ co-doped NaLa(MoO4)2 exhibited weak red emissions near 660 nm and 670 nm and strong green UC emissions at 530 nm and 550 nm corresponding to the intra 4f transitions of Er3+ (4F9/2, 2H11/2, 4S3/2) → Er3+ (4I15/2). The optimum doping concentrations of Er3+ and Yb3+ for the highest emission intensity were determined by using X-ray diffraction (XRD) and photoluminescence (PL) analyses. The Er3+/Yb3+ (7.0/10.0 mol%) co-doped NaLa(MoO4)2 phosphor sample exhibited a strong, shiny, green emission. A possible UC mechanism for Er3+/Yb3+ co-doped NaLa(MoO4)2 depends on the pump power is discussed in detail.