Near-infrared downconversion luminescence of SrMoO4:Tm3+,Yb3+ phosphors

Tm3+ and Yb3+ codoped SrMoO4 phosphors were synthesized by the high-temperature solid-state reaction method. The structure, ultraviolet-visible diffuse reflectance spectra, photoluminescence, decay properties and theoretical energy transfer efficiency of the phosphors were investigated in detail. The electronic structure and band gap of SrMoO4 were estimated by density functional theory (DFT) calculation. The XRD results show that all the prepared phosphors can be readily indexed to scheelite-type structure. The strong visible emission around 473 nm from Tm3+ ((1)G(4) -> H-3(6)) and near-infrared (NIR) emission around 998 nm from Yb3+ (F-2(5/2) -> F-2(7/2)) of the SrMoO4:Tm3+,Yb3+ phosphors were observed under 283 nm excitation. The dependence of the visible and NIR emissions on Yb3+ concentration have also been investigated. The quenching concentration of Yb3+ ions approaches 10 mol%. In addition, the energy transfer processes and possible transfer routes were proposed. (C) 2017 Elsevier Ltd. All rights reserved.