Optical Temperature Sensor Based on Er³⁺/Yb³⁺-Codoped Perovskite BaZrO₃

The Er³⁺/Yb³⁺-codoped perovskite BaZrO₃ (BaZrO₃:Er³⁺, Yb³⁺) phosphor was synthesized via a simple, rapid, and cost-effective pyrolysis reaction. The perovskite crystals BaZrO₃:Er³⁺, Yb³⁺ have a Goldschmidt tolerance factor of 0.9-1 and belong to the cubic crystal system. BaZrO₃:Er³⁺ emits strong green luminescence when excited by a 980-nm laser. The addition of Yb³⁺ can tune the emission color of BaZrO₃:Er³⁺ from green to yellow and red. BaZrO₃:Er³⁺, Yb³⁺ was investigated as temperature probes for optical temperature sensors. The performance of the temperature sensor was evaluated over the temperature range of 293-473 K. Using the fluorescence intensity ratio (FIR) technique based on the thermally coupled levels (TCLs) of the two emission bands (²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2), the maximum relative sensitivity of the sensor was 1.03 × 10^-2 K^-1 at 293 K.