Preparation and Characterization of Gd203：Eu^3＋ Sol-Gel Thin Films for X-Ray Imaging

With the pretreatment of pyrolysis, the uni-form, smooth, dense and crack free Gd203:Eu^3 films were obtained by sol-gel process without shielding at mosphere. Atomic force microscopy (AFM), X-ray diffraction (XRD), Ellipsometry, transmission, photoluminescence and X-ray excited emission were applied to study to the surface morphology, structure,thickness and optical properties of the films. The resuits show that the films are made up of grains with cubic structure in average size about 22 nm. With 21 times reproducible spin coating and pyrolysis treatment, the thickness of the film could reach to 792 nm and the transmittance of the film in visible region is above 90%. Two peaks at 223 and 250 nm are found in excitation spectra, which correspond to host lattice(HL) excitation and charge transfer (CT) excitation,respectively. Meanwhile, the main peak relates to HLexcitation which is contrary to that of Gd203:Eu^3 powder. This phenomenon will be beneficial to radioluminescence. The emission spectra show that the main peak located at 611 nm could be excited either by UV or X-ray, which correspond to ^7F2→5D0 transition in Eu3 ions. The luminescence intensity at 10 ms is only 10^-4 time of that at 10 tLs, which means that the afterglow in Gd203:Eu^3 films is insignificant for X-ray imaging.