title: Template-based fabrication of SrTiO3 and BaTiO3 nanotubes.
abstract: In response to the growing need for metal oxide nanotubes and nanowires for nanoelectronic applications, polycrystalline titanate nanotubes are synthesized in this work at near-ambient conditions without the application of an external electric field or pre-existing solids. Nanotubes of complicated metal oxides including strontium titanate and barium titanate are fabricated inside anodic aluminum oxide (AAO) templates from aqueous solutions using a simple, inexpensive, reproducible, and environmentally friendly procedure. The deposition solution is prepared by dissolving ammonium hexafluorotitanate and strontium nitrate in a boric acid solution at a pH of 2.5. The typical lengths of SrTiO(3) nanotubes are 5-30 microm, with an average diameter of approximately 250 nm, which is defined by the pore diameter of the AAO template. After annealing at 800 degrees C in air, the resulting nanotubes are polycrystalline cubic SrTiO(3). The Sr:Ti ratio in the nanotube is controlled by the hydrolysis of TiF(6)(2-) ions, and the concentration of Sr(2+) and stoichiometric SrTiO(3) nanotubes can be obtained. As an additional controlling factor, the surface properties of the AAO can be modified by (octadecyl)trichlorosilane. Barium titanate is also prepared in a similar manner with barium nitrate and ammonium hexafluorotitanate as precursors. The polycrystalline cubic BaTiO(3) nanotubes are 12-30 microm long and approximately 250 nm in diameter.
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, Taipei 115, Republic of China.
authors.forename: Ying-Yu
authors.initials: YY
authors.lastname: Chen
authors.forename: Bang-Ying
authors.initials: BY
authors.lastname: Yu
authors.forename: Jung-Hui
authors.initials: JH
authors.lastname: Wang
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Cochran
authors.forename: Jing-Jong
authors.initials: JJ
authors.lastname: Shyue