Double-site emission of Eu2+ ions in Sr4Al14O25: Eu2+ phosphors for self-calibrated optical thermometry

Abstract Eu 2+ activated aluminate Sr 4 Al 14 O 25 with dual-emitting centers were prepared via a solid-state method in a reductive atmosphere. Photoluminescence emission (PL) and excitation (PLE) spectra of phosphor along with the lifetimes were characterized, which confirm the 5d→4f energy transition behavior of Eu 2+ between 400 nm and 490 nm emission. The fluorescence intensity ratio of I 490 and I 400 in the phosphors exhibits remarkable temperature dependence, owing to the diverse thermal quenching behaviors of Eu 2+ emission centers. Using the phosphors to perform thermometry, excellent temperature sensitivity is achieved in the temperature range of 293–423 K. The maximum absolute and relative sensitivity are 0.004 K -1 and 0.624% at 373 K, respectively. In particular, the dual-site luminescence of Eu 2+ ions can be used as the reference signal and the temperature signal of the fluorescence temperature sensor respectively. It will be helpful to develop a new self-reference optical temperature measurement technology with excellent performance.