Synthesis of color-tunable Sr8MgLa(PO4)7:Eu3+/Tb3+ phosphors for designing dual-model thermometers

Abstract A series of Tb3+ and Eu3+ ions single and co-doped Sr8MgLa(PO4)7 (SMLPO) phosphors have been successfully prepared. The SMLPO:0.3 Tb3+/yEu3+ phosphors exhibit color-tunable performances while the energy transfer mechanism between Tb3+ and Eu3+ is determined to be the quadrupole-quadrupole interaction. Besides, the dual-model techniques for optical thermometers based on the ratiometric emission peak and fluorescence lifetime are introduced. The sensing sensitivity is investigated by using the integral intensity ratio between the Eu3+ (5D0→7F2, 616 nm) transition and the Tb3+ (5D4→7F5, 544 nm) transition, and its maximum relative sensitivity (SR1) value reaches up to be 1.3 % K−1 at 573 K. Meanwhile, the temperature-sensitive characteristic based on the fluorescence lifetime is identified by fitting the temperature variable lifetime while the obtained SR2 is found to be about 0.7 % K−1 at 573 K. These results demonstrate that SMLPO:Tb3+/Eu3+ phosphors with color-tunable performances and good sensing sensitivities are potential for dual-model thermometers.