Anti-thermal quenching and temperature sensing properties of Er³⁺/Yb³⁺ co-doped Sc₂O₃ phosphors

Up-conversion luminescence from rare earth doped phosphor is a potential candidate as non-contact temperature sensor. In this work, different Er³⁺ concentration doped Sc₂O₃: Er³⁺/Yb³⁺ phosphors were prepared through typical sol-gel method. The emission intensity reached the maximum as the doping concentration of Er³⁺ was 1.0 mol%. While, different from high concentration (0.5, 1.0 and 2.0) of Er³⁺ doped samples, an abnormal enhancement in the two green emissions and red emission in Sc₂O₃: 0.3 mol% Er³⁺/2 mol% Yb³⁺ phosphors was observed through elevate temperature and the enhancement factor reaches 1.3 as the temperature changed from 303 to 513 K. The reason for this concentration dependent thermal enhancement could be interpreted by the competition between increased energy transfer and non-radiative transition. The temperature sensing properties of samples, including relatively sensitivity, temperature resolution and repeatability were investigated and the maximum values reached 1.03 × 10^-2 K^-1 (303 K), 0.524 K (303 K) and 99.65 % (303--513 K), respectively, in Sc₂O₃: 1 mol% Er³⁺/2 mol% Yb³⁺ phosphors. The results imply that they have good temperature sensing ability and can be used as an optical temperature probe in research and production.