Highly sensitive Tm3+/Yb3+ codoped SrWO4 for optical thermometry

In this paper, Tm3+/Yb3+ codoped SrWO4 materials for optical thermometry is synthetized and characterized. Under a 980 nm diode laser excitation, the upconversion emission spectra of the material under different temperature were measured in the temperature range of 308 K-573 K. The fluorescence intensity ratios (FIRs) of the Tm3+:3F2 → 3H6 (684 nm) and Tm3+:3F3 → 3H6 (696 nm) emissions to the Tm3+:3H4 → 3H6 (814 nm) emission were respectively calculated. The results show that the natural logarithm of both FIRs change linearly with the reciprocal of temperature. The maximum absolute sensitivities are 0.00544 K−1 and 0.00617 K−1 at 323 K, respectively, which are about one order higher than that of most of the previously reported Tm3+/Yb3+ doped materials with other hosts. The results indicate that SrWO4:Tm3+/Yb3+ is a very promising material for highly sensitive optical thermometry.