Photoluminescence/cathodoluminescence properties and energy transfer mechanisms of fine-particle Gd2O2S:Tb3+, RE3+ (RE = Dy, Eu) phosphor

Gd2O2S:Tb3+, RE3+ (RE = Dy, Eu) phosphors were prepared by molten salt method and the samples were characterized by XRD, SEM, photoluminescence, cathodoluminescence and thermal stabilization. XRD results indicated that phosphors were pure hexagonal crystal structure and Dy3+ and Eu3+ sensitizers successfully occupied the Gd3+ sites. Granularity test results indicated that the average particle size of the powder was 2 μm. The effect of Eu3+ sensitizer on Tb3+ luminescence was discussed for the first time in the photoluminescence spectra. The results verified that the efficient emission of Tb3+ was sensitized by Dy3+/Eu3+ under the excitation of 288 nm/296 nm. 382 nm, 415 nm and 438 nm, which correspond to the 5D3 → 7FJ (J = 6, 5 and 4) of Tb3+, respectively, and 488 nm, 544 nm, 587 nm, 622 nm, which correspond to the 5D4 → 7FJ (J = 6, 5, 4 and 3) of Tb3+, respectively. There was also a weak emission peak of Dy3+ was seen at 576 nm (4F9/2 → 6H13/2) in Gd2O2S:Tb3+, Dy 3+. And weak emission peaks of Eu3+ were seen at 617 nm and 625 nm (5D0 → 7F2) in Gd2O2S:Tb3+, Eu 3+. The sensitizers of Dy3+ and Eu3+ not only effectively enhanced the photoluminescence of Tb3+ through electric quadrupole-electric quadrupole interactions and electric dipole-electric quadrupole interactions, respectively, but also effectively improved the thermal stability of Gd2O2S:Tb3+ through energy transfer. Increasing acceleration voltage could further enhance the powder's cathodoluminescence. Gd2O2S:Tb3+, Dy3+ phosphor had higher cathodoluminescence properties.