Optical temperature sensing of Er3+/Yb3+ doped LaGdO3 based on fluorescence intensity ratio and lifetime thermometry

The investigation of the fluorescence intensity ratio and the lifetime thermometry techniques for two rare earth perovskites-type oxide (LaGdO3:Er3+ and LaGdO3:Er3+/Yb3+) has been carried out. We have demonstrated that the intensity ratio of thermally coupled levels of erbium (H-2(11/2) and S-4(3/2)) is temperature dependant in the range from 283 to 393 K. The sensitivity parameter was found to reach a maximum value of 31 x 10(-4) K-1 and 34 x 10(-4) K-1 at 393 K and the temperature resolution to be equivalent to 1.61 and 3.1 K, for Er3+ and Er3+/Yb3+ doped oxide, respectively. By studying the temperature dependence of the normalized lifetimes in the range from 293 to 348 K, we proved that the sensitivity of the green emission (S-4(3/2)) is higher than the red one (F-4(9/2)) for both samples, and that it increases from 144 x 10(-4) K-1 for LaGdO3:Er3+ to 179 x 10(-4) K-1 for LaGdO3:Er3+/Yb3+. The thermal coefficients were quite large in comparison to those calculated for different luminescent materials and reported in literature. The repeatability of measurements was tested by performing heating and cooling cycles for both methods and the results show that these optical techniques have a good repeatability performance. Hence, the LaGdO3: Er3+, Yb3+ oxide has a precise and a satisfying sensitivity associated to a good thermal and chemical stability, suggesting that it can be a potential candidate in temperature sensing. (C) 2017 Elsevier B.V. All rights reserved.