Pure red upconversion luminescence and optical thermometry of Er3+ doped sensitizer-rich SrYbInO4 phosphors
Er3+ doped sensitizer-rich SrYbInO4 upconversion phosphors with an orthorhombic structure (Pnma) were synthesized by using a high temperature solid state reaction and their phase structure, site occupation and microstructure have been analyzed. Interestingly, upon the excitation from 980 nm pulsed laser diodes, the SrYbInO4:Er3+ phosphor emitted a nearly pure red emission on account of the 4F9/2 → 4I15/2 transition of Er3+. Additionally, based on the pump power dependence of the upconversion intensity and the schematic diagram of the energy levels, the upconversion mechanism in this system was verified in a two-photon process. The temperature-dependent behaviors of the as-synthesized sample demonstrated the potential for applications in optical thermometry.