A qualitative test for intrinsic size effect on ferroelectric phase transitions

TL;DR

This paper introduces a qualitative test for intrinsic size effects in ferroelectric phase transitions, highlighting polarization rotation driven by size and temperature variations, demonstrated through PbTiO3 nanowires.

Contribution

It proposes a new qualitative approach to identify intrinsic size effects in ferroelectrics based on polarization rotation phenomena.

Findings

Size effect causes polarization rotation in ferroelectrics.

Size effect induces an additional phase transition.

Polarization rotation serves as a qualitative indicator of size effects.

Abstract

The size effect in ferroelectrics is treated as a competition between the geometrical symmetry of the ferroelectric sample and its crystalline symmetry. The manifestation of this competition is shown to be polarization rotation, which is driven by temperature and/or size variations, thus providing a qualitative indication of intrinsic finite size effect on ferroelectrics. The concept is demonstrated in a simple case of PbTiO3 nanowires having their axis parallel to [111]C direction, where the size effect is shown to include polarization rotation and an additional phase transition.