title: Enhanced polarization by the coherent heterophase interface between polar and non-polar phases.
abstract: A piezoelectric composite containing the ferroelectric polar (Bi(Na0.8K0.2)0.5TiO3: f-BNKT) and the non-polar (0.94Bi(Na0.75K0.25)0.5TiO3-0.06BiAlO3: BNKT-BA) phases exhibits synergetic properties which combine the beneficial aspects of each phase, i.e., the high saturated polarization (Ps) of the polar phase and the low coercive field (Ec) of the non-polar phase. To understand the origin of such a fruitful outcome from this type of polar/non-polar heterophase structure, comprehensive studies are conducted, including transmission electron microscopy (TEM) and finite element method (FEM) analyses. The TEM results show that the polar/non-polar composite has a core/shell structure in which the polar phase (core) is surrounded by a non-polar phase (shell). In situ electrical biasing TEM experiments visualize that the ferroelectric domains in the polar core are aligned even under an electric field of ∼1 kV mm(-1), which is much lower than its intrinsic coercive field (∼3 kV mm(-1)). From the FEM analyses, we can find that the enhanced polarization of the polar phase is promoted by an additional internal field at the phase boundary which originates from the preferential polarization of the relaxor-like non-polar phase. From the present study, we conclude that the coherent interface between polar and non-polar phases is a key factor for understanding the enhanced piezoelectric properties of the composite.
authors.affiliation: Materials Modeling & Characterization Department, Korea Institute of Materials Science, Changwon 642-831, South Korea. sdkim@kims.re.kr youngchoi@kims.re.kr and School of Materials Science and Engineering, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Gi-Yeop
authors.initials: GY
authors.lastname: Kim
authors.affiliation: Materials Modeling & Characterization Department, Korea Institute of Materials Science, Changwon 642-831, South Korea. sdkim@kims.re.kr youngchoi@kims.re.kr.
authors.forename: Kil-Dong
authors.initials: KD
authors.lastname: Sung
authors.affiliation: Materials Modeling & Characterization Department, Korea Institute of Materials Science, Changwon 642-831, South Korea. sdkim@kims.re.kr youngchoi@kims.re.kr.
authors.forename: Youngmok
authors.initials: Y
authors.lastname: Rhyim
authors.affiliation: School of Materials Science and Engineering, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Seog-Young
authors.initials: SY
authors.lastname: Yoon
authors.affiliation: Battery Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, South Korea.
authors.forename: Min-Soo
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Battery Research Center, Korea Electrotechnology Research Institute, Changwon 641-120, South Korea.
authors.forename: Soon-Jong
authors.initials: SJ
authors.lastname: Jeong
authors.affiliation: School of Materials Science and Engineering, Pusan National University, Pusan 609-735, South Korea.
authors.forename: Kwang-Ho
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Functional Ceramics Group, Korea Institute of Materials Science, Changwon 642-831, South Korea.
authors.forename: Jungho
authors.initials: J
authors.lastname: Ryu
authors.affiliation: Materials Modeling & Characterization Department, Korea Institute of Materials Science, Changwon 642-831, South Korea. sdkim@kims.re.kr youngchoi@kims.re.kr.
authors.forename: Sung-Dae
authors.initials: SD
authors.lastname: Kim
authors.affiliation: Materials Modeling & Characterization Department, Korea Institute of Materials Science, Changwon 642-831, South Korea. sdkim@kims.re.kr youngchoi@kims.re.kr.
authors.forename: Si-Young
authors.initials: SY
authors.lastname: Choi