Abstract
One-dimensional (1D-) metallic and semiconducting nanostructures (nanowires,nanorods, and nanotubes) have attracted considerable attentions due totheir striking fundamental properties and potential applications innano-scale electronic devices including field-effecttransistors\cite{melosh:electronic},opto-electronic devices\cite{huang:laser}, sensors\cite{cui:sensor}, and light-emittingdiodes\cite{bjork:diode}. In the recent years, 1D-piezoelectric/ferroelectricnanostructures are also stimulating more researches for fundamentalfinite size effects and potential applications in such as nanoactuators,nanoelectromechanical systems. In contrast to the template-assistedpreparation of polycrystalline ferroelectric 1D-nanostructures\cite{cao:review,morrison1}, this paperreports one two-step hydrothermal route to synthesize lead-freehigh Curie temperature piezoelectric BaTi$_2$O$_5$\cite{tillmanns} single crystalline nanowiresthrough monitoring nucleation and growth processes bymeans of controlling the shape of nucleus. For a typical case ofBaTi$_2$O$_5$ nanowires prepared at 90$^o$C for 1 h with titaniananotubes prepared at 170$^o$C for 17.5 h as titanium resource,BaTi$_2$O$_5$ nanowires exhibited a diameter between 20-500 nm andlength of 1-10 $\mu m$. The formation mechanism of BaTi$_2$O$_5$nanowires was discussed from the viewpoint of lattice structure. The piezoelectric coefficient for theBaTi$_2$O$_5$ nanowires was preliminarily measured as about -9 pm/V at room temperature.This method does not require any template, membrane,surfactant or applied external field to create anisotropicnanoparticle or to control their growth orientation, whichenables the growth of ferroelectric titanate nanowires atlarge-scale and very low temperatures.
