Designing dual-emission phosphors for temperature warning indication and dual-mode luminescence thermometry.

Color tunable phosphors of Mn 4+ and Tb 3+ co-doped double-perovskite SrGdLiTeO 6 (SGLT) were synthesized in this work. The crystal parameters and photoluminescence performances were investigated in detail. By taking advantage of the different thermal quenching strengths between Mn 4+ and Tb 3+ ions, the emission color of SGLT:0.7%Mn 4+ /1%Tb 3+ changed from red to green, which could be used for high-temperature temperature warning indication. Moreover, according to the luminescence intensity ratio (LIR) technique, wide temperature-range optical thermometry was developed and further, the maximum relative sensitivity ( S R1 ) value of the SGLT:0.7%Mn 4+ /5%Tb 3+ phosphor was determined to be 1.49% K -1 at 560 K. On the other hand, the sensing properties were also analyzed based on the temperature-dependent lifetime method. The most interesting thing is that the maximum S R2 value reached 1.88% K -1 at 573 K. This work proved that the Mn 4+ and Tb 3+ co-doped double-perovskite SrGdLiTeO 6 could be potentially used in temperature warning indication and high sensitivity luminescence thermometry.