Enhanced temperature sensing performance of Er3+, Yb3+: PLZT ceramic based on emissions of Stark sublevels.

In this study, the temperature sensing behaviors of emissions of Stark sublevels in Er³⁺/Yb³⁺ codoped lead lanthanum zirconate titanate (PLZT) transparent ceramic were examined. Based on the temperature-dependent upconversion fluorescence spectra excited by 980 nm, the emission intensities of the Stark sublevels ²H_{11/2(1, 2)}, ⁴S_{3/2(1, 2),} and ⁴F_{9/2(1, 2, 3)} were obtained upon increasing the temperature from 160 to 320 K. All the transitions present strong temperature dependence under the competitive effects of thermal excitation and nonradiative relaxation. The optical temperature sensing properties of ²H_11/2/⁴S_3/2(1), ²H_11/2/⁴S_3/2(2), ²H_11/2/⁴F_9/2(1), ²H_11/2/⁴F_9/2(2), and ²H_11/2/⁴F_9/2(3) were investigated using the fluorescence intensity ratio (FIR) technique. The largest absolute sensitivity S_a of 142.4 × 10^–4 K⁻¹ was obtained based on the FIRs of ²H_11/2/⁴F_9/2(1) at 320 K, which is approximately 26 times larger than that of traditionally used thermal coupled levels ²H_11/2/⁴S_3/2 in the considered sample. In contrast, the maximum relative sensitivity S_r was 2.21% K⁻¹ at 203 K. A comparison of these results with those of other Er³⁺/Yb³⁺ codoped materials reveals that Er³⁺/Yb³⁺: PLZT ceramics are a promising thermometer material at low temperatures. Applying FIRs based on the photoluminescence of Stark sublevels is a practical approach to achieving greater thermometric efficiency. [ABSTRACT FROM AUTHOR]