Design and fabrication of a bimodal emitting phosphor by co-doping two different activators for high sensitivity temperature sensing

Designing of phosphors with multi-emission peaks that show incongruent response to temperature is crucial to design high-efficiency optic fluorescence temperature sensors. Herein, Mn4+ and Dy3+ were co-doped into host lattice Ca2InSbO6 (CIS) with bimodal emissions for fluorescence intensity ratio (FIR) thermometry. The Dy3+-luminescence is insensitive to temperature for its 4f→4f transitions whereas the Mn4+-luminescence is sensitive for its outer 3d→3d transitions. This feature causes almost unchanged intensity of Dy3+-luminescence with increasing temperature and fast decay of Mn4+-luminescence. Utilized the inconsistent temperature dependency of phosphor CIS:Mn4+/Dy3+, highly absolute sensitivity (Sa) of 9.10% K−1 at 573 K and relative sensitivity (Sr) of 2.16% K−1 at 498 K are realized. Additionally, the fluorescence lifetime of Mn4+ is also sensitive to the temperature with Sa of 0.17% K−1 at 348 K and Sr of 1.890 %K−1 at 423 K. This work gives a design idea for researchers in optic temperature sensor field that a phosphor with double activated ions of Dy3+ and Mn4+ is a good choice.