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 Eu3+ and Eu2+ ions at different K3YSi2O7 lattice sites. In the luminescence-intensity-ratio strategy, a ratiometric signal composed of Eu3+:5D0→7F1 and Eu3+:5D0→7F2 emissions at 593 and 616 nm, respectively, is employed. Meanwhile, the intensity ratio of the 593-nm emission under O2-→Eu3+ charge transfer excitation (λex = 249 nm) to that upon Eu2+:4f7→4f65d1 excitation (λex = 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.