Photoluminescence and Temperature Sensing Properties of Bi3+/Sm3+ Co-Doped La2MgSnO6 Phosphor for Optical Thermometer

The optical temperature sensor utilizing the fluorescence intensity ratio (FIR) has garnered significant attention in the past few years due to its rapid response, robust anti-interference capability, remote control feature, and other advantages. In this study, the high-temperature solid-phase approach was used to fabricate a variety of double perovskite-structured La2MgSnO6: Bi3+, Sm3+ (LMS: Bi3+, Sm3+) phosphors. The Rietveld refinement data of XRD and the Gaussian fitting of the emission peak of LMS: 0.02Bi3+ phosphor indicated Bi3+ occupies three lattice sites. The calculation and analysis of average lifetime and energy transfer efficiency substantiated the presence of energy transfer from Bi3+ to Sm3+, with a transfer efficiency of up to 59.07%. The emission intensity of LMS: 0.02Bi3+, 0.05Sm3+ at 403 K maintains 50.2% at the condition of room temperature. The FIR fitting and calculation demonstrated that LMS: 0.02Bi3+, 0.05Sm3+ phosphor possessed good optical temperature sensitivity, with a maximum absolute sensitivity Sa-max of 0.0055 K−1 and a maximum relative sensitivity Sr-max of 0.88% K−1, demonstrating its valuable potential applications for optical temperature sensors.