Luminescence properties and optical sensing behaviors of Sr2GdSbO6:Eu3+ phosphors

Novel orange-red Sr2GdSbO6:xEu3+ (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) phosphors were successfully prepared by the traditional high-temperature solid-state method. The results of Rietveld refinement, energy dispersive spectroscopy (EDS) spectrum and elemental mapping demonstrate that Eu3+ successfully replaces the Gd3+ sites and distributes uniformly in the particles of phosphors. The luminescence properties of Sr2GdSbO6:Eu3+ phosphors were investigated in detail. The emission spectra of the strongest emission peak is the 5D0→7F1 (593 nm) transition, which can emit orange-red light under 393 nm excitation. When the doping concentration of Eu3+ ions is x = 0.2, the luminescence intensity of the phosphors reaches the highest. The detailed mechanism of concentration quenching is attributed to dipole-dipole interaction. The thermal stability values of Sr2GdSbO6:0.2Eu3+ phosphors are 87%, 82% and 114% under 393, 467 and 527 nm excitations, respectively. The causes of the abnormal thermal quenching under 527 nm excitation were analyzed. Based on the abnormal thermal quenching under 527 nm excitation, the optical thermometry properties of Sr2GdSbO6:0.2Eu3+ phosphors were investigated by fluorescence intensity ratio (FIR) technique, and appreciable relative sensitivity was obtained. The results suggest that Sr2GdSbO6:0.2Eu3+ phosphors can be potentially applied to w-LEDs and optical thermometers.