title: Revealing the core-shell interactions of a giant strain relaxor ferroelectric 0.75Bi1/2Na1/2TiO3-0.25SrTiO3.
abstract: Lead-free relaxor ferroelectrics that feature a core-shell microstructure provide an excellent electromechanical response. They even have the potential to replace the environmentally hazardous lead-zirconia-titanate (PZT) in large strain actuation applications. Although the dielectric properties of core-shell ceramics have been extensively investigated, their piezoelectric properties are not yet well understood. To unravel the interfacial core-shell interaction, we studied the relaxation behaviour of field-induced ferroelectric domains in 0.75Bi1/2Na1/2TiO3-0.25SrTiO3(BNT-25ST), as a typical core-shell bulk material, using a piezoresponse force microscope. We found that after poling, lateral domains emerged at the core-shell interface and propagated to the shell region. Phase field simulations showed that the increased electrical potential beneath the core is responsible for the in-plane domain evolution. Our results imply that the field-induced domains act as pivotal points at the coherent heterophase core-shell interface, reinforcing the phase transition in the non-polar shell and thus promoting the giant strain.
authors.affiliation: Institute of Materials Science and Center of Smart Interfaces, Physics of Surfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany.
authors.forename: Na
authors.initials: N
authors.lastname: Liu
authors.affiliation: Insititute of Materials Science, Nichtmetallische-Anorganische Werkstoffe, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt, Germany.
authors.forename: Matias
authors.initials: M
authors.lastname: Acosta
authors.affiliation: Insititute of Materials Science, Mechanik funktionaler Materialien, Technische Universität Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.affiliation: Insititute of Materials Science, Mechanik funktionaler Materialien, Technische Universität Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
authors.forename: Bai-Xiang
authors.initials: BX
authors.lastname: Xu
authors.affiliation: Institute of Materials Science and Center of Smart Interfaces, Physics of Surfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Stark
authors.affiliation: Institute of Materials Science and Center of Smart Interfaces, Physics of Surfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Dietz