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

In this study, a dual-mode optical thermometer is designed based on radiative transitions from Eu and Eu ions at different KYSiO lattice sites. In the luminescence-intensity-ratio strategy, a ratiometric signal composed of Eu:D→F and Eu:D→F emissions at 593 and 616 nm, respectively, is employed. Meanwhile, the intensity ratio of the 593-nm emission under O→Eu charge transfer excitation (λ= 249 nm) to that upon Eu:4f→4f5d excitation (λ= 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.