Correlation between optical thermometry and Judd–Ofelt parameters in Er3+-doped perovskite oxides

Abstract

We investigate the optical thermometric performance of Er³⁺-doped perovskite oxides with thermally coupled levels (TCLs). We obtain their optical thermometric parameters, such as their fluorescence intensity ratio and temperature sensitivity, from upconversion luminescence spectra under 980 nm excitation over a wide temperature range. Subsequently, we systematically compare these experimentally determined parameters with theoretical predictions for a TCL system, in addition to parameters derived from Judd–Ofelt (J–O) analysis, which is a well-established theoretical framework that describes the radiative transitions and intensities of rare-earth (RE) ions. A close correspondence between the experimental and theoretical results is achieved when the temperature-dependent variation of the J–O parameters and the TCL gap is considered. Our findings provide valuable insights into the roles of host-lattice effects, local crystal field variations, and defect-related phenomena in governing the thermal response of RE ion-doped phosphors for optical thermometry applications.