Dual-mode optical thermometry design in K3YSi2O7:Eu multi-site phosphor

In this study, a dual-mode optical thermometer is designed based on radiative transitions from Eu 3+ and Eu 2+ ions at different K 3 YSi 2 O 7 lattice sites. In the luminescence-intensity-ratio strategy, a ratiometric signal composed of Eu 3+ : 5 D 0 → 7 F 1 and Eu 3+ : 5 D 0 → 7 F 2 emissions at 593 and 616 nm, respectively, is employed. Meanwhile, the intensity ratio of the 593-nm emission under O 2− →Eu 3+ charge transfer excitation (λ ex = 249 nm) to that upon Eu 2+ :4f 7 →4f 6 5d 1 excitation (λ ex = 349 nm) is selected as a thermometric parameter in the single-band-ratio approach. The study findings show that combining the two strategies is conducive to the improvements in sensing-sensitive and anti-interference performance.