Ferroelectricity enhancement in ferroelectric nanotubes

TL;DR

This study investigates how size and surface effects influence ferroelectric properties in nanotubes, deriving an analytical expression for transition temperature and predicting polarization enhancement in long nanotubes.

Contribution

The paper provides an analytical model for ferroelectric transition temperature dependence on nanotube size and surface effects, explaining observed ferroelectricity enhancement.

Findings

Transition temperature can exceed bulk values for negative electrostriction.

Polarization is conserved and enhanced in long ferroelectric nanotubes.

Results explain experimental observations in Pb(Zr,Ti)O3 and BaTiO3 nanotubes.

Abstract

In this paper we study the size effects of the ferroelectric nanotube phase diagrams and polar properties allowing for effective surface tension and depolarization field influence. The approximate analytical expression for the paraelectric-ferroelectric transition temperature dependence on the radii of nanotube, polarization gradient coefficient, extrapolation length, surface tension and electrostriction coefficient was derived. It was shown that the transition temperature could be higher than the one of the bulk material for negative electrostriction coefficient. Therefore we predict conservation and enhancement of polarization in long ferroelectric nanotubes. Obtained results explain the observed ferroelectricity conservation and enhancement in Pb(Zr,Ti)O_3 and BaTiO_3 nanotubes.