Enhanced bipolar fatigue-resistance and optical temperature sensing in Er-modified 0.94(Bi 0.5 Na 0.5 )TiO 3 -0.06(K 0.5 Na 0.5 )NbO 3 lead-free ceramics

Abstract 0.94Bi0.5Na0.5TiO3-0.06 K0.5Na0.5NbO3-xEr ceramics were prepared by the conventional solid-state reaction, and their bipolar fatigue and optical temperature sensing properties were investigated. Results showed that the addition of Er3+ led to the reduced NaBiO3 phase, which could effectively improve their fatigue behavior. Strong green upconversion luminescence from the two thermally coupled 2H11/2 and 4S3/2 levels of Er3+ was recorded in the temperature range from 20 °C to 200 °C under 980 nm laser excitation. The maximum sensing sensitivity was found to be 0.0022 K−1.