Separation of K+ and Bi3+displacements in a Pb-free, monoclinic piezoelectric at the morphotropic phase boundary

Surta, T Wesley ORCID: 0000-0002-2882-6483, Keeney, Lynette, Manjon-Sanz, Alicia M, Crawford, Catriona, Morscher, Alexandra, Daniels, Luke M ORCID: 0000-0002-7077-6125, Claridge, John B ORCID: 0000-0003-4849-6714, Bell, Andrew J, Alaria, Jonathan ORCID: 0000-0001-5868-0318 and Rosseinsky, Matthew J ORCID: 0000-0002-1910-2483 (2024) Separation of K+ and Bi3+displacements in a Pb-free, monoclinic piezoelectric at the morphotropic phase boundary ACTA MATERIALIA, 265. 119594-. ISSN 1359-6454, 1873-2453

Access the full-text of this item by clicking on the Open Access link.

Abstract

The best piezoelectric properties of any perovskite oxide known are found in the solid solution of the relaxor Pb(Mg<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf> and ferroelectric PbTiO<inf>3</inf>. Despite its impressive properties, this system has limited analogy. We present the compositional exploration of the Pb-free analogue (1-x)(K<inf>1/2</inf>Bi<inf>1/2</inf>)(Mg<inf>1/3</inf>Nb<inf>2/3</inf>)O<inf>3</inf>-x(K<inf>1/2</inf>Bi<inf>1/2</inf>)TiO<inf>3</inf> (KBMN-KBT). We locate the morphotropic phase boundary between x = 0.86 and 0.88 changing from Cm to Pm symmetry and the optimally performing composition at x = 0.88. We report a piezoelectric figure of merit (d<inf>33</inf>*) of 192 pm V⁻¹ from strain measurements. Diffraction methods reveal disordered displacements of K⁺ and Bi³⁺ which persist from the KBMN endmember through multiple changes in symmetry. Rearrangement of the Bi³⁺ displacements along the uncommon [011]<inf>c</inf> direction drives the physical response. Ferroelectric, dielectric, and piezoresponse force microscopy are used to study the progression of physical properties through the MPB and attribute the mechanism to a polarization rotation. Taking account for local, short-range, and average structural features yield a balanced perspective on the structure and properties of this system, isolating the driving force within this system to the Bi³⁺ bonding configuration. This work yields a strong analogy to the Pb-based analogue, and provides strategies for further optimization.

Item Type:	Article
Uncontrolled Keywords:	Perovskite oxide, Relaxor, Piezoelectric, Ferroelectric, Structural analysis
Divisions:	Faculty of Science & Engineering > School of Physical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	21 Dec 2023 13:41
Last Modified:	16 Jun 2026 17:07
DOI:	10.1016/j.actamat.2023.119594
Open Access URL:	https://doi.org/10.1016/j.actamat.2023.119594
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3177586
Disclaimer:	The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate.