KNN-based Optical Temperature Sensing Ceramics Integrating Negative Thermal Quenching and Photochromic Self-Recovery Behavior

Rare-earth ion (RE3+) doped materials with upconversion luminescence and photochromic (PC) effect have received widespread attention, but thermal quenching (TQ) at high temperature and energy-demanding PC recovery processes limit their practical applications. Herein, lanthanide ion doped (K0.5Nb0.5)NbO3 (KNN) based translucent ceramics were prepared, in which Tm3+/Yb3+ co-doped one displays optical versatility for potential applications in temperature sensors and anti-counterfeiting. By utilizing the large energy mismatch between Tm3+ and Yb3+, negative thermal quenching (NTQ) feature was achieved with the maximum relative sensitivity of 2.54 %K-1 at 213 K. Furthermore, by constructing appropriate intermediate traps, the ceramic exhibits a rapid PC self-recovery process within 30 min without external stimulation. The bifunctional specialty can expand the applications of KNN-based ceramics in optical area.