Temperature sensing properties of NaYTiO4: Yb/Tm phosphors based on near-infrared up-conversion luminescence

In this study, NaYTiO4: Yb/Tm phosphors with different concentrations of Yb3+ and Tm3+ ions were synthesized by conventional solid-state reaction. Upon a 980 nm laser excitation, the up-conversion luminescence properties in a wide temperature range (303-823 K) were investigated. By employing the fluorescence intensity ratio (FIR) techniques based on the robust near-infrared emissions of thermally coupled F-3(2,3)/H-3(4) energy levels and H-3(4(1))/H-3(4(2)) Stark energy levels, the calculated absolute sensitivity (S-a), relative sensitivity (S-r), and temperature uncertainty (delta T) values demonstrated good temperature sensing properties. For the F-3(2,3)/H-3(4) energy levels, the maximum S-r and minimum delta T values are 1.04% K-1 and 0.010 K at 463 K, respectively. Moreover, the maximum S-a is 0.32 x 10(3 )K(-1) at 823 K. In addition, the thermally coupled H-3(4) Stark energy levels present the maximum S-a, S-r and the minimum delta T are 0.88 x 10(-3) K-1, 0.60% K-1 and 3.17 K at 303 K, respectively. Besides, due to the ratio of blue to red emission varying with elevated temperature, the NaYTiO4: Yb/Tm phosphors are expected to be applied as an intuitive high-temperature indicator.

Automated summary

In this study, NaYTiO4: Yb/Tm phosphors with different concentrations of Yb3+ and Tm3+ ions were synthesized and their up-conversion luminescence properties at different temperatures were investigated. The fluorescence intensity ratio technique was employed to demonstrate the good temperature sensing properties of the phosphors, which can be potentially applied as a high-temperature indicator.