Dynamic stable nanostructured metal oxide fractal films grown on flat substrates

Well-organized, dynamic stable nanostructured oxide films, especially transition-metal oxide films have applications in areas of wide scope but are difficult to be grown from solution directly due to the high-temperature requirement in most formation processes which usually destroys the dynamic stable nanostructures. A novel synthetic method associated with a spin coating procedure broke the confinement and produced many different dendrite-like nanostructured fractal films directly on flat substrates from solutions at room temperature, for example, ZnO, Al₂O₃, TiO₂, Nb₂O₅, WO₃, and so forth. In two dimensions, theses fractal films show abundant surface structures like cypress leaf, daisy, fish bone, fern leaf, tree root, and so forth, and their growth and dimensions comply with the reaction-limited aggregation (RLA) mechanism. Experimental results show that the morphology and dimensionality of the FFs is strongly dependent on the chemical compositions and the interactions between particles and the substrate surfaces. The stronger the interaction between the particles and the surfaces, the more even the films, while the stronger the interaction among the particles, the thicker the films.