Influence of. γ-radiation on photoluminescence properties of YPO4:Eu3+, Ce3+ and YPO4:Dy3+,Ce3+ phosphors

Hexagonal YPO4 phosphors doped with Eu3+/Dy3+ and co-doped with Ce3+ were synthesized by a hydrothermal route assisted using lauric acid as a capping agent. The prepared phosphors were characterized by transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction and photoluminescence spectra. YPO4: Eu3+ gives two red emission peaks at 587 and 610nm corresponding to (D0F1)-D-5-F-7 and (D0F2)-D-5-F-7 transitions, respectively. YPO4: Dy3+ exhibits two emission peaks at 485nm (blue) and 575nm (yellow) corresponding to (F9/2H15/2)-F-4-H-6 and (F9/2H13/2)-F-4-H-6 transitions, respectively. Ce3+ ions enhanced the emission intensity as a co-dopant in both phosphors. Moreover, the effect of -radiation in the dose range 5-300kGy on the photoluminescence behaviour of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ was also investigated. Quenching of emission intensity, after irradiation at 5 and 300kGy, was observed in both the phosphors due to loss of excess energy through a non-radiative relaxation process.