[Luminescence properties of Eu, Dy doped BaAl12 O19 long afterglow phosphors]

Long afterglow phosphors BaAl12 O19:Eu2+/Eu3+, Dy3+ were synthesized by high temperature solid state method under different atmosphere. X-ray powder diffraction (XRD) shows that pure BaAl12 O19 phase structure was obtained and the do ping ions Eu2+/Eu3+, Dy3+ didn't change the phase structure. By comparison, the authors found that the doping ions Eu2+/ Eu3+, Dy3+ caused the XRD diffraction peaks moving to the high angle slightly which displayed that the inter-planar spacing was changed via Eu and Dy replacing Ba lattice in BaAl12 O19. Emission spectra show that all the samples prepared under different conditions exhibit the 4f6 5d1 --> 4J7 broadband transition which is the features emission of Eu2+ and the existence of the features emission of Eu2+ in the sample synthesized in air indicates that Eu3+ ions can be reduced to divalent state in air. The doping ions Dy3+ can not only enhance the luminous intensity of samples but also make the samples to obtain long afterglow characteristics. The afterglow decay and thermoluminescence studies of the Eu, Dy co-doped sample synthesized under reducing atmosphere reveal that the sample has good long afterglow properties at room temperature and high temperature.