Optical thermometry based on fluorescence intensity ratio of Dy3+-Doped oxysilicate apatite warm white phosphor

The development of non-contact thermometers is one of the important applications of phosphors. In this work, a photoluminescence strategy by introducing Dy 3+ for application in fluorescence intensity ratio thermometry (FIR) was investigated in detail. The FIR approach employs the fluorescence intensity ratios of 4 I 15/2 - 6 H 15/2 and 4 F 9/2 - 6 H 13/2 , due to the Boltzmann variant distribution between two excited states at specific temperatures. The crystal structure, morphology, and luminescence behaviors of CaLa 4 (SiO 4 ) 3 O: Dy 3+ were studied. When the excitation wavelength is 348 nm, two strong emission peaks of CaLa 4-x (SiO 4 ) 3 O: xDy 3+ at 478 and 573 nm respectively, as well as two small emission peaks located at 456 nm and 661 nm. The optical temperature measurement performance of the phosphors at different temperatures (298 K–548 K) was achieved because of the different thermal quenching transitions of 4 F 9/2 - 6 H 15/2 and 4 F 9/2 - 6 H 13/2 . The maximum relative sensitivity and absolute sensitivity of the as-prepared phosphors as optical thermometers could reach as high as 0.1673% K −1 at 298 K and 0.007087% K −1 at 548 K, respectively. Therefore, we hope that our research on the temperature measurement of CaLa 4 (SiO 4 ) 3 O: Dy 3+ series phosphors can lay a certain research foundation and reference value for the subsequent research on the temperature measurement direction of Dy 3+ doped phosphors.