Up-conversion luminescence of Yb[formula omitted]/Er[formula omitted] doped Gd[formula omitted] phosphors for optical temperature sensing in green and red regions

Abstract

In this work, the up-conversion luminescence of Yb 3+/Er3+ doped Gd2O3 phosphors for optical temperature sensing in green and red regions are investigated. The intense green (522 and 562 nm) and red emissions (660 and 682 nm) radiated from Er3+/Yb3+ tri-doped Gd2O3 phosphors are successfully realized via tuning the doping proportion of Er3+ and Yb3+. To evaluate their potential ability of optical thermometry in green light range and the first biological window, the temperature-dependent green and red emissions are investigated. Based on the florescence intensity ratio (FIR) of 522 and 562 nm, the absolute sensing sensitivities of Gd2O3: 1 mol% Er3+/4 mol% Yb3+ and Gd2O3: 1 mol% Er3+/6 mol% Yb3+ phosphors reach 1.16 and 1.2% K−1 (523 K), respectively. In addition, the temperature sensing sensitivities based on the FIR of 660 and 682 nm reach 0.8 and 0.6% K−1 (300 K), respectively. Moreover, the changes of FIR (ΔR) are smaller than 3% within the cycling heat and cool processes. These results reveal that Gd2O3:1mol%Er/4(6)mol%Yb phosphors are promising for FIR-based temperature sensing in high temperature via green emissions and room temperature via red emissions.