Li/Ag ratio dependent structure and upconversion photoluminescence of LixAg1−xYb0.99(MoO4)2:0.01Er3+ phosphors

Abstract

A series of double molybdate scheelite-type phosphors Li_xAg_1−xYb_0.99(MoO₄)₂:0.01Er³⁺ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were synthesized by the solid state reaction method, and their crystal structures and upconversion (UC) luminescence properties were investigated in detail. The phase structure evolution of this series samples was discussed and the selected Li_0.5Ag_0.5Yb_0.99(MoO₄)₂:0.01Er³⁺ was analyzed based on the Rietveld refinement. The UC emission properties and the related UC mechanism were also studied. With an increasing Li/Ag ratio in this host, the UC emission intensities of Li_xAg_1−xYb_0.99(MoO₄)₂:0.01Er³⁺ increased obviously, and the enhancement could be attributed to the coupling effect and the nonradiative transition between two energy levels of Li_xAg_1−xYb(MoO₄)₂ matrices and the activator Er³⁺, which have also been analyzed based on the results of the ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS) and Raman spectroscopy.