Ferroelectric Nanotubes: From Fabrication to Property Control

Ferroelectric materials have a wide range of applications owing to their anisotropic physical properties, such as a high dielectric constant, pyroelectricity, and piezoelectricity. The high piezoelectric coefficient of Pb(Zr,Ti)O3 (PZT) (d33 = 200‒600 pC/N) makes it one of the most widely used ferroelectric materials. Ferroelectric nanostructures are considered highly promising for applications, such as actuators, transducers, and energy harvesters. We report the template-directed growth of PZT nanotubes by combining a sol-gel process with spin coating. Field-emission scanning electron microscopy (FESEM) images show that the PZT nanotubes are well packed inside the pores of a porous alumina membrane (PAM). A well-saturated hysteresis loop is observed in these ferroelectric PZT nanotubes, confirming their ferroelectric switching behavior. The piezoresponse of the nanotubes is quantitatively evaluated, and free-standing nanotubes are found to exhibit a higher response than nanotubes clamped by the PAM. These results suggest that lateral clamping can reduce the piezoresponse. These PZT nanotube arrays may offer a route toward artificial skin, touchpads, bio-imaging, and nanogenerators.