Synthesis, Microstructural And Optical Properties Of Pr³⁺ Doped 12CaO·7Al₂O₃ Powders

Pr³⁺-doped 12CaO·7Al₂O₃ (C12A7:Pr³⁺) powders were prepared using thecoprecipitation method.The microstructure and optical properties were investigated andmeasured by XRD, excitation and emission spectra, fluorescence lifetime, afterglow decay,thermoluminescence and photostimulated luminescence. Based on a series of experiments, itis shown that C12A7 is an ideal material. C12A7:Pr³⁺ has higher emission peak at 491 nm,three-wavelength phosphorescence and two-wavelength optical storage, it can be used instorage field as one kind of potential multi-dimension recording materials.Through analyzes the XRD to be possible to discover that we already obtained have thespecial cage shape structure phase sole C12A7 powder, has not appeared with the Pr³⁺related X-ray diffraction peak, moreover Pr³⁺ possibly mixes to the crystal physique position.Has surveyed the C12A7:Pr³⁺ powder excitation spectrum and the emission spectrum usingthe fluorescence spectroscope.The emission peaks at 491 nm, 535 nm and 614 nm,corresponding to the transition 3P0→3H4, 3P0→3H5 and 1D2→3H4 of Pr³⁺ ions. The excitationpeaks at 230 nm, 447 nm, 474 nm, 486 nm,corresponding to the transition 4f2-4f15d1, 3H4 to3P2,3P1,3P0.After the samples were irradiated by UV light (230 nm) for 5 min and placed in the darkfor 5 min to drain the afterglow, the long afterglow emission contain 491 nm, 535 nm and 614nm, the time of the afterglow emission is about 300 s. The intensity of the three kind colorsphosphorescence weakens gradually along with the time. The afterglow decay curve have anextremely quick process and an extremely slow process, so C12A7:Pr³⁺ has a low trap and adeep trap. In accordance with the thermoluminescence spectrum, the depth of the trap isabout 0.63 eV. The intensive photostimulated luminescence(PSL)of C12A7:Pr³⁺ isobserved under infrared exciation (808 nm) due to the existence of the shallow traps. Thedecay of the photostimulated luminescence demonstrates that this sample is suit able to beused as recording material for two-wavelength optical storage, most of all, the intensity ofphotostimulated luminescence is stable. Consequently, the recording density is very ideal.