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.

Controllable Template-Assisted Electrodeposition of Single- and Multi-Walled Nanotube Arrays for Electrochemical Energy Storage

“…Various methods have been developed for the synthesis of nanotubes, such as high temperature evaporation6, colloidal growth7, hydrothermal synthesis89, anodic oxidation101112, and template- and surfactant-assisted growth tech-niques131415161718192021222324. Recently, there is increasing interest in the template-assisted method because it has been used to synthesize various nanotubes composed of many types of materials, such as silica2526, metal oxides272829, polymers3031, and biological macromolecules32.…”

1D core–shell magnetoelectric nanocomposites by template-assisted liquid phase deposition

“…Based on replica lithography, Deki and coworkers fabricated highly ordered vertically aligned iron oxide nanopillars using the LPD technique. 20 Our group reported recently on the fabrication of uniform spinel ferrite M x Fe 3-x O 4 (M=Ni, Co, Zn) 21 and ABO 3 (A=Ba and Sr) 22 nanotube arrays with diameters of 200 nm by using the LPD route combined with a template-assisted approach. As the use of the conventional measurement set-up for bulk magnetoelectric composites is very limited to nanostructures due to difficulties in the separation of the ME signal and noise, recently complementary experimental techniques, such as Raman spectroscopy and scanning probe microscope (SPM) have been introduced to magnetoelectric characterization of bilayered nanocomposites.…”

BaTiO3‐based nanolayers and nanotubes: First‐principles calculations

“…The ferroelectric phase transition in the BTO NT arrays covered a wide temperature range, which resulted in the coexistence of the tetragonal and cubic phases above 150 C. The authors [12] came to the conclusion that the inner stress as well as the size effect in the BTO NT arrays is responsible for the slightly enhanced Curie temperature and the diffuse ferroelectric phase transition. [12] NTs of complicated metal oxides including STO and BTO have been fabricated inside the anodic aluminum oxide [13] or porous silicon [14] templates from aqueous solutions. Resulting BTO NTs are straight, smooth and have a very high aspect ratio.…”

“…Depending on the templates, their outer diameter ranges from 50 nm up to several micrometers. The tube walls of BTO NTs consist of a polycrystalline cubic phase [13] or ferroelectricphase [14] layers. Thus, measurements [6,14] indicated that BTO NTs with sufficiently thick walls possess ferroelectric properties.…”