[Preparation and luminescence properties of transparent Gd2O3 : Eu thick film]

High-resolution X-ray imaging systems require materials with good scintillation performances, especially X-ray absorption performance. Compared with powder phosphors display devices, those with transparent crystalline phosphors are very interesting due to their higher contrast and resolution for having no optical scattering, superior thermal conductivity as well as high degree of uniformity and better adhesion. Europium-doped gadolinlum oxide is a promising candidate due to its high density (7.62 g x cm(-3)), good light yield (18.5 x 10(3) photons/MeV), and the red emission of Eu3+ ion. The sol-gel method is one of the most important techniques for deposition of functional films, because it possesses a number of advantages over conventional film formation techniques, such as low processing temperature, easy coating of large surfaces, and homogenous multicomponent oxide films. In X-ray imaging application, the thickness of the film is the most important factor for commercial use, which can increase X-ray absorption of the film and then strengthen its luminescence yield. In the present work, transparent Gd2 O3 : Eu3+ thick film was successfully prepared using sol-gel method and spin-coating technique by choosing Ln2 O3 (Ln = Gd, Eu) as raw materials, 2-methoxyethanol as solvent, PVP as adhesive and PEG200 as surface modifier. The film was homogeneous and crack free. The thickness of the film could achieve 1.5 microm after 2 times of coating, and its transmittance was approximately 80% in visible region. It was shown that PVP played an important role in film preparation, which could suppress stress and increase viscidity of the sol. In addition, the excitation, emission and decay time of the Gd2 O3 : Eu3+ scintillator film were studied. Their performances were quite good, which implied that the film would have promising applications in high-spatial-resolution X-ray imaging and flat panel display devices.