Ferroelectric effects in PZT

TL;DR

This study uses first-principles calculations to explore how alloying and ferroelectric effects influence the bonding and hybridization in lead zirconate titanate (PZT), revealing key changes in covalency and effective charges.

Contribution

It provides new insights into the atomic bonding and hybridization mechanisms underlying ferroelectricity in PZT with high Ti composition.

Findings

Two sets of B-O bonds in paraelectric PZT: Ti-O and Zr-O.

Formation of covalent Ti-O bonds and Pb-O chains in ferroelectric phase.

Enhanced hybridization reduces effective charges in the ferroelectric phase.

Abstract

First-principles calculations are performed to investigate alloying and ferroelectric effects in lead zirconate titanate (PZT) with high Ti composition. We find that the main effect of alloying in the paraelectric phase of PZT is the existence of two sets of B-O bonds, i.e., shorter Ti-O bonds vs. longer Zr-O bonds. On the other hand, ferroelectricity leads to the formation of very short covalent Ti-O bonds and to the formation of covalent chains of Pb-O bonds. The covalency in the ferroelectric phase is mainly induced by an enhancement of hybridization between Ti 3d and O 2p, and between Pb 6s and O 2p. These hybridizations induce a striking decrease of the effective charges when going from the paraelectric to the ferroelectric phase of PZT.