Random lattice strain and its relaxation towards the morphotropic phase boundary of Na0.5Bi0.5TiO3-based piezoelectrics: Impact on the structural and ferroelectric properties

Das Adhikary, Gobinda and Khatua, Dipak Kumar and Senyshyn, Anatoliy and Ranjan, Rajeev (2019) Random lattice strain and its relaxation towards the morphotropic phase boundary of Na0.5Bi0.5TiO3-based piezoelectrics: Impact on the structural and ferroelectric properties. In: PHYSICAL REVIEW B, 99 (17).

PDF Phy_Rev_99_17_2019.pdf - Published Version Restricted to Registered users only Download (3MB) | Request a copy

Abstract

We demonstrate that the lead-free piezoelectric compound Na0.5Bi0.5TiO3 (NBT) exhibits random lattice strain in the ferroelectric phase, and that this feature primarily dictates the way the system evolves towards the morphotropic phase boundary in the unpoled state of NBT-based piezoelectrics. Investigations on two different morphotropic phase boundary (MPB) systems, namely Na0.5Bi0.5TiO3 - K0.5Bi0.5TiO3 (NBT-KBT) and Na0.5Bi0.5TiO3 - BaTiO3 (NBT-BT), revealed that the coupled structural-polar evolution towards the MPB is primarily driven by the necessity to minimize this strain. Our study suggests that the random lattice strain originates in the random stacking of the in-phase tilt and antiphase octahedral tilted regions, and that the system is able to minimize it by adopting a sequential stacking of the two tilt types, leading to a long-period modulation in the octahedral tilt configuration over large parts of the sample volume. This hinders the development of long-range ferroelectric order as the MPB is approached. We also demonstrate that the composition showing the maximum piezoelectric coefficient corresponds to a structural state wherein considerable polar-structural disorder coexists with the field-stabilized long-range rhombohedral ferroelectric order after poling, and not coexistence of two ferroelectric phases (tetragonal and rhombohedral), generally believed.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	copyright for this article belongs to PHYSICAL REVIEW B
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	24 Jun 2019 20:15
Last Modified:	24 Jun 2019 20:15
URI:	http://eprints.iisc.ac.in/id/eprint/63051

Actions (login required)

View Item