Dual-mode optical thermometers based on YNbO4:Bi3+,Sm3+ phosphors

Herein, YNbO4:Bi3+,Sm3+ phosphors were fabricated via conventional solid-phase reaction. A thorough evaluation of their structure, morphology, photoluminescence properties and energy transfer from Bi3+ to Sm3+ was carried out, along with the investigation of temperature sensing capabilities. Excited by 312 nm, YNbO4:Bi3+,Sm3+ phosphors exhibit broadband emission from transition of 3P1 to 1S0 of Bi3+ and characteristic emission peaks from 4f-4f transitions of Sm3+. Using color-coordinate and fluorescence intensity ratio (FIR) dual modes, YNbO4:Bi3+,Sm3+ phosphors show good temperature sensitivity. The maximum relative sensitivity (Sr-max) of x and y coordinates reach 0.43%K−1 at 450 K and 0.54%K−1 at 460 K, respectively. The Sr-max of FIR is 1.52%K−1 at 458 K. These results indicate that YNbO4:Bi3+,Sm3+ phosphors offer possibility for designing a dual-mode optical thermometer.