Hydrothermal synthesis of thin films of barium titanate ceramic nano-tubes at 200 degrees C

A novel, low-temperature synthesis method for producing BaTiO3 thin films patterned in the form of nano-tubes (honeycomb) on Ti substrates is reported. In this two-step method, the Ti substrate is first anodized to produce a surface layer (similar to200-300-nm thickness) of amorphous titanium oxide nanotube (similar to100-nm diameter) arrays. In the second step, the anodized substrate is subjected to hydrothermal treatment in aqueous Ba(OH)(2), where the nano-tube arrays serve as templates for their hydrothermal conversion to polycrystalline BaTiO3 nano-tubes. This opens the possibility of tailoring the nano-tube arrays and of using various precursor solutions and their combinations in the hydrothermal bath, to produce ordered, patterned thin-film structures of various Ti-containing ceramics. These could find use not only in a variety of electronic device applications but also in biomedical applications, where patterned thin films are also desirable.