Enhancing piezoelectricity through polarization-strain coupling in ferroelectric superlattices

TL;DR

This study uses density functional theory to explore how polarization-strain coupling in ferroelectric superlattices enhances piezoelectricity, revealing a peak at 75% PTO concentration due to bulk property effects.

Contribution

It demonstrates the enhancement of piezoelectric response in BTO/PTO superlattices driven by polarization-strain coupling, with predictions based on an effective Hamiltonian.

Findings

Polarization remains nearly constant below 50% PTO.

Significant decrease in c/a ratio below PTO values.

Peak d33 piezoelectric coefficient at ~75% PTO concentration.

Abstract

Short period ferroelectric/ferroelectric BaTiO3 (BTO)/PbTiO3 (PTO) superlattices are studied using density functional theory. Contrary to the trends in paraelectric/ferroelectric superlattices the polarization remains nearly constant for PTO concentrations below 50%. In addition, a significant decrease in the c/a ratio below the PTO values were observed. Using a superlattice effective Hamiltonian we predict an enhancement in the d33 piezoelectric coefficient peaking at ~75% PTO concentration due to the different polarization-strain coupling in PTO and BTO layers. Further analysis reveals that these trends are bulk properties which are a consequence of the reduced $P$ brought about by the polarization saturation in the BTO layers.