A novel high-sensitive optical thermometer based on the multi-color emission in Pr3+ doped LiLaMgWO6 phosphors

Abstract Nowadays, optical thermometric materials with high sensing sensitivity in a wide temperature interval are urgently required due to the appealing prospect in the field of sensing technology. Herein, the double perovskite Pr3+: LiLaMgWO6 phosphors are successfully prepared via a high-temperature solid-state reaction method, and their concentration/temperature-dependent luminescence properties are discussed systematically. Upon UV excitation, the samples emit blue (3P0→3H4), green (3P0,1 → 3H5) and red emissions (1D2→3H4, 3P0→3F2) from Pr3+ ions. The different changing tendencies in relation to temperature are observed for the emissions from 3P0 and 1D2 multiplets, which are attributed to the effects of cross-over process to Pr3+-W6+ intervalence charge transfer (IVCT) state, cross relaxation process and multiphonon relaxation process. When the fluorescence intensity ratio (FIR) between 3P0→3F2 (654 nm) and 1D2→3H4 (616 nm) transitions is applied for temperature sensing, 0.5%Pr3+: LiLaMgWO6 displays a maximum absolute sensing sensitivity of 2421 × 10−4 K−1 at 573 K. Moreover, it can keep a comparatively high relative sensitivity (1%~3.25% K−1) and low temperature uncertainty (0.15–0.5 K) over a wide temperature range (~280 K), which are superior to those of many luminescence materials reported previously. The present study may provide useful design information to develop high-sensitive luminescent thermometers with a wide applicable temperature range.