Up-conversion luminescence transparent CaNb2O6 glass ceramics for temperature monitoring

To explore new up-conversion luminescent materials with high sensitivity for optical thermometry, Yb3+/Tm3+ co-doped transparent CaNb2O6 glass ceramics are successfully prepared using the traditional melting and controlling crystallization. Its structure, micro-morphology and luminescence characteristics are studied comprehensively by means of XRD, Raman, TEM and a fluorescence spectrometer. The results show that the luminescence intensity of glass ceramics is significantly higher than that of glasses under 980 nm laser excitation. A dual-mode temperature measurement based on fluorescence intensity ratios (FIR, I690/I796 and I690/I651) is realized by using the different temperature dependence of emission peaks of Tm3+. In a wide temperature range (298 − 573 K), the highest absolute sensitivity (Sa-max) of 0.42‰ K−1 and the supreme relative sensitivity (Sr-max) of 2.65% K−1 based on thermal coupling energy levels (TCELs) are gained. Furthermore, using non-thermal coupling energy levels (NTCELs), Sr-max and Sa-max reach 0.23% K−1 and 20.49% K−1, respectively. This work indicates that the CaNb2O6 glass ceramics as a new type of up-conversion luminescent material have great application prospects in the field of optical thermometry.