A dual-mode self-referenced optical thermometry with high sensitivity based on Er3+-Yb3+ co-doped Sr2YTaO6 thermochromic phosphor

Up conversion luminescent materials Sr 2 YTaO 6 : Er 3+ , Yb 3+ phosphors were prepared by high temperature calcination . In view of the formation, temperature characteristics , and photoluminescence features of the sample, X-ray diffraction and photoluminescence were used. Under the excitation at 980 nm, the series of samples is significantly stimulated by Er 3+ up-conversion luminescence and Yb 3+ sensitization at 524, 550 and 659 nm. According to the diversity of temperature sensing performance from these three highest peaks, a dual-mode temperature sensor on account of fluorescence intensity ratio (thermally coupled level between 2 H 11/2 and 4 S 3/2 , and nonthermally coupled energy levels between 2 H 11/2 and 4 F 9/2 ) is achieved by using a single luminescent center. Moreover, the phosphor has strong thermal stability, which is helpful to improve the accuracy of temperature measurement. Under the temperature measurement of a dual-mode temperature sensor, it is calculated that the optimal absolute sensitivity S a of thermally coupled energy level is 0.78 × 10 −3  K −1 (473 K) and relative sensitivity S r is 1.32 %K −1 (293 K), and the maximum optimal absolute sensitivity S a of non-thermally coupled energy level is 1.02 × 10 −4  K −1 (473 K) and relative sensitivity S r is 0.58 %K −1 (293 K). All results imply that Sr 2 YTaO 6 : Er 3+ , Yb 3+ phosphors are promising materials for self-referenced optical temperature measurement.