title: Piezoelectricity and rotostriction through polar and non-polar coupled instabilities in bismuth-based piezoceramics.
abstract: Coupling of order parameters provides a means to tune functionality in advanced materials including multiferroics, superconductors, and ionic conductors. We demonstrate that the response of a frustrated ferroelectric state leads to coupling between order parameters under electric field depending on grain orientation. The strain of grains oriented along a specific crystallographic direction, 〈h00〉, is caused by converse piezoelectricity originating from a ferrodistortive tetragonal phase. For 〈hhh〉 oriented grains, the strain results from converse piezoelectricity and rotostriction, as indicated by an antiferrodistortive instability that promotes octahedral tilting in a rhombohedral phase. Both strain mechanisms combined lead to a colossal local strain of (2.4 ± 0.1) % and indicate coupling between oxygen octahedral tilting and polarization, here termed "rotopolarization". These findings were confirmed with electromechanical experiments, in situ neutron diffraction, and in situ transmission electron microscopy in 0.75Bi1/2Na1/2TiO3-0.25SrTiO3. This work demonstrates that polar and non-polar instabilities can cooperate to provide colossal functional responses.
authors.affiliation: Department of Geo- and Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
authors.forename: Matias
authors.initials: M
authors.lastname: Acosta
authors.affiliation: Department of Geo- and Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
authors.forename: Ljubomira A
authors.initials: LA
authors.lastname: Schmitt
authors.affiliation: School of Materials Science and Engineering, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors.forename: Claudio
authors.initials: C
authors.lastname: Cazorla
authors.affiliation: Bragg Institute, Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC NSW 2232, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Studer
authors.affiliation: Department of Geo- and Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Zintler
authors.affiliation: School of Materials Science and Engineering, UNSW Australia, Sydney, New South Wales 2052, Australia.|Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim, 7491, Norway.
authors.forename: Julia
authors.initials: J
authors.lastname: Glaum
authors.affiliation: Department of Geo- and Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Kleebe
authors.affiliation: Department of Geo- and Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Donner
authors.affiliation: School of Materials Science and Engineering, UNSW Australia, Sydney, New South Wales 2052, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Hoffman
authors.affiliation: Department of Geo- and Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rödel
authors.affiliation: School of Materials Science and Engineering, UNSW Australia, Sydney, New South Wales 2052, Australia.|Institute for Applied Materials, Karlsruhe Institute for Technology, P.O. Box 3640, 76021 Karlsruhe, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Hinterstein