Morphology controlled fabrication and ferroelectric properties of vertically aligned one-dimensional lead titanate nanoarrays.

Vertically aligned nanowires and highly uniform nanoporous array thin films of PbTiO(3) are synthesized by varying anodic oxidation conditions of Ti foil followed by hydrothermal reaction in an aqueous Pb(II) acetate trihydrate solution. As-synthesized samples have single crystalline nanowire structure and polycrystalline nanoporous structure, although both are pure PbTiO(3) with a tetragonal phase. The structure of intermediate TiO(2) films obtained from different anodic oxidation conditions determines the structure of the product PbTiO(3). The relationships between these morphological structures and ferroelectric properties are investigated. Piezoresponse force microscopy reveals that both these films show ferroelectricity with clear phase contrast and well-defined hysteresis loops. The saturated longitudinal piezoelectric coefficient field (E(c)) of the nanowire sample is smaller than that of nanoporous thin film. Thus, polarization of nanowire thin film is larger in magnitude and easier to flip than that of nanoporous film.

Growth of single crystalline barium titanate nanowires from TiO2 seeds deposited on conducting glass.

A new synthetic method is reported for depositing BaTiO(3) nanowire film on conducting glass. First, a TiO(2) particle thin film is prepared by spray coating, and then transformed to single crystalline BaTiO(3) nanowires grown on the conducting glass by hydrothermal treatment using TiO(2) particles as seeds of nanowire growth. The BaTiO(3) nanowires are 50-100 nm in diameter and have a film thickness of 4 µm. The capacitance of the BaTiO(3) one-dimensional (1D) nanowire array film was found to be 4.5 times higher than that of the nanoparticle film by measuring the impedance. The piezoelectric property of an individual BaTiO(3) nanowire was also demonstrated by piezoforce microscopy.