Preparation and Characterization of NaGdF4:Eu3+/AAO Thin Films

NaGdF4:Eu3+/AAO thin films were prepared on porous anodic aluminum oxide(AAO) template surface via a hydrothermal process and the effects of preparing method, the amount of NaGdF4:Eu3+ and the annealing temperature were investigated. The crystal structure, morphology and luminescent properties of the-as-prepared NaGdF4: Eu3+/AAO thin films were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM) and photoluminescence(PL) spectra. XRD results show that the phase transition of NaGdF4:Eu3+/AAO thin films from the hexagonal phase to the cubic phase occurs at about 500 degrees C in air. SEM images indicate that the preparing method influences obviously the morphology of NaGdF4:Eu3+/AAO thin films, NaGdF4:Eu3+/AAO thin films with the rectangle morphology were prepared by two-step hydrothermal process, and however the one-step hydrothermal process was employed to prepare NaGdF4:Eu3+/AAO thin films without any special morphology. The amount of NaGdF4:Eu3+ in the solution and the annealing temperature do not obviously affect the morphology of NaGdF4:Eu3+/AAO thin films. PL results show that the characteristic emission of NaGdF4:Eu3+/AAO thin films with hexagonal or cubic NaGdF4 structure is D-5(0) -> F-7(2) transition of Eu3+.