Effect of Yb3+ concentration on tunable upconversion luminescence and optically temperature sensing behavior in Gd2TiO5:Yb3+/Er3+phosphors

Abstract

The color-tunable upconversion (UC) emission and optical temperature sensing behavior was observed from the Er-Yb codoped Gd2TiO5 (GTO) phosphors synthesized by the simple sol-gel method. By control of the Yb3+ concentration, the phosphors are capable of generating color tunable UC luminescence from yellowish green to yellow, then to orange. The tunable emission is due to the energy back transfer from Er3+ to Yb3+ and the cross relaxation between the two neighboring Er3+ ions. The temperature dependence of the fluorescence intensity ratios (FIR) of two green UC emissions in Gd2TiO5:Yb3+/Er3+ phosphors with different Yb3+ doping concentration have been studied in the range of 298–573 K under 980 nm laser diode excitation and the maximum sensitivities were approximately 40.76 × 10−4 K−1 at 565 K. The above results suggest that the as-prepared Gd2TiO5:Yb3+/Er3+ phosphors have great potential for the applications of lightings and optical temperature sensors.