Size influence on optical thermometry of Er3+/Yb3+ Co-doped Y2O3 microspheres: From TCLs and Non-TCLs

Abstract

Realization and optimization of enhanced/tunable optical luminescence properties is highly demanded for reliable and accurate temperature sensing. In this work, uniform monodisperse spherical Er3+/Yb3+ co-doped Y2O3 microcrystals of four different sizes have been synthesized via homogeneous precipitation by changing the reaction time, and the tuning of luminescence intensity/color was achieved by the controllable particles size. On this basis, by studying the particle size dependence of temperature sensing performance, we found that the behavior of absolute sensitivity (Sa) and relative sensitivity (Sr) have highly size dependence. Interestingly, when different FIR strategies were used (thermally coupled levels (TCLs) and nonthermally coupled levels (non-TCLs)), the sensitivity exhibits the opposite behavior. Importantly, when using the non-TCLs strategy, the maximum Sa value for the smallest phosphors was 1.084 K-1, leading to ∼246 times improvement compared to TCLs-based Sa. The ultrahigh Sa indicated that the Er3+/Yb3+ co-doped Y2O3 phosphors have potential in temperature detection, and the results are of guiding significance to studying the sensitivity of Y2O3 particle size-dependent temperature measurement.