Synthesis and photoluminescent properties of Y₂O₃:Eu³⁺thin films prepared from F127-containing solution

Dense and transparent Y₂O₃:Eu³⁺films were prepared by the solgel process and dip-coating technique from an yttrium 24 pentanedionate, europium nitrate and a methanol solution modified with F127 pluronic acid, by incorporation of acetic acid as pH modifier and acetylacetone as sol stabilizer. It was evaluated the effect of the F127/Y molar relationship (0, 0.1, 0.2, 1.0, 1.2 and 5.0) on the structure and photoluminiscent properties of the derived thin films. After 3 dipping-cycles, XRD results showed that the F127-modified films began to crystallize at 600°C into the cubic structure, and from 800°C, was found that the presence of F127 changes the preferential orientation from a (100) orientation, for the non-modified sample, to a (111) orientation, for the modified ones. M-lines spectroscopy characterization showed that the maximum thickness of the films modified and annealed at 900°C was 1937nm (p = 4.87 g cm^-3, n = 1.887), compared with the 881nm (p = 4.94 g cm^-3, n = 1.907) for a non-modified sample. Differential thermal analysis (DTA) and infrared spectroscopy (FTIR) were carried out to evaluate the chemical and structural evolution of the xerogel formed during the annealing process. AFM micrographs showed smooth crack-free surface (Ra = 9.2 nm) on a F127/Y = 0.2 sample. Finally, the films presented a typical Eu3+ reddish emission at 611 nm (D_o→⁷F₂), which was analyzed as function of the F127 pluronic content and the annealing temperature.