Upconversion luminescence and temperature sensing properties of Tm³⁺, Yb³⁺, and Ho³⁺ doped 12CaO·7Al₂O₃ single crystals

Abstract

Tm3+, Yb3+, and Ho3+ doped 12CaO·7Al2O3 (C12A7) single crystal exhibiting white light emission has been successfully prepared by the Czochralski method. Under 980 nm excitation, the emission peaks were observed at 475 nm, 550 nm, 653 nm, and 660 nm. As the temperature increased from 403 K to 623 K, the upconversion luminescence color of the Tm3+/Yb3+/Ho3+/C12A7 crystal changed from white to green and exhibited large temperature dependence. In the temperature range of 403K-623 K, the absolute sensitivity (SA) value of the thermal coupling levels (TCLs) fluorescence intensity ratio (FIR, I700/I800) was 1.48×10−5K−1, and the relative sensitivity (SR) value was 7.13×10−3%K−1. The non-thermal coupling levels (NTCLs) FIR (I800/I870) had an SA value of 0.026K−1 and an SR value of 0.014%K−1, which achieved a significant increase in temperature sensitivity compared to the former. It provides a strategy to achieve accurate sensitivity of FIR technology. Rare earth (RE) ions doped C12A7 single crystal material has good research and application prospects in the field of temperature sensing and optoelectronics.