Strategy for realizing ratiometric optical thermometry via efficient Tb3+-Mn2+ energy transfer in novel apatite-type phosphor Ca9Tb(PO4)5(SiO4)F2

The novel apatite-type phosphor Ca9Tb(PO4)(5)(SiO4)F-2:Mn2+ (CTPSF:Mn2+) has been successfully synthesized and it demonstrated a potential for optical thermometry. The energy transfer process between Tb3+ and Mn2+ was of resonant type via a dipole-dipole mechanism based on the Inokuti-Hirayama theoretical model, and the energy transfer (ET) efficiency and ET rate were estimated. In view of the energy transfer behavior, a strategy, involving the use of Tb3+ and Mn2+ dual-emitting centers with different thermal quenching behavior, has been developed to achieve temperature sensitivity and good signal discrimination. The temperature dependence of the fluorescence intensity ratios (FIR) for the dual-emission bands peaking at 548 and 595 nm was studied in the range of 298-573 K under excitation of 377 nm ultraviolet light and the maximum relative sensitivity was approximately 1.92% K-1 at 423 K. It is expected that this preliminary study will provide an important advance in exploring novel ratiometric optical thermometry. (C) 2018 Elsevier B.V. All rights reserved.