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

Color tunable phosphors of Mn and Tb co-doped double-perovskite SrGdLiTeO (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 and Tb ions, the emission color of SGLT:0.7%Mn/1%Tb 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 () value of the SGLT:0.7%Mn/5%Tb phosphor was determined to be 1.49% K 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 value reached 1.88% K at 573 K. This work proved that the Mn and Tb co-doped double-perovskite SrGdLiTeO could be potentially used in temperature warning indication and high sensitivity luminescence thermometry.