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 ORCID: 0000-0003-0980-514X, Manjón-Sanz, Alicia M, Crawford, Catriona ORCID: 0000-0003-3806-8687, Morscher, Alexandra ORCID: 0000-0001-9850-1222, Daniels, Luke M ORCID: 0000-0002-7077-6125, Claridge, John B ORCID: 0000-0003-4849-6714, Bell, Andrew J ORCID: 0000-0002-2061-3862, 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. p. 119594.

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Abstract

The best piezoelectric properties of any perovskite oxide known are found in the solid solution of the relaxor Pb(Mg1/3Nb2/3)O3 and ferroelectric PbTiO3. Despite its impressive properties, this system has limited analogy. We present the compositional exploration of the Pb-free analogue (1-x)(K1/2Bi1/2)(Mg1/3Nb2/3)O3-x(K1/2Bi1/2)TiO3 (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 (d33*) 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]c 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
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 21 Dec 2023 13:41
Last Modified: 01 Feb 2024 13:42
DOI: 10.1016/j.actamat.2023.119594
Open Access URL: https://doi.org/10.1016/j.actamat.2023.119594
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3177586
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