title: Impact of Isovalent and Aliovalent Doping on Mechanical Properties of Mixed Phase BiFeO3.
abstract: In this study, we report the effect of doping in morphotropic BiFeO3(BFO) thin films on mechanical properties, revealing variations in the elasticity across the competing phases and their boundaries. Spectroscopic force-distance (F-D) curves and force mapping images by AFM are used to characterize the structure and elastic properties of three BFO thin-film candidates (pure-BFO, Ca-doped BFO, La-doped BFO). We show that softening behavior is observed in isovalent La-doped BFO, whereas hardening is seen in aliovalent Ca-doped BFO. Furthermore, quantitative F-D measurements are extended to show threshold strengths for phase transitions, revealing their dependence on doping in the system. First-principles simulation methods are also employed to understand the observed mechanical properties in pure and doped BFO thin films and to provide microscopic insight on them. These results provide key insight into doping as an effective control parameter to tune nanomechanical properties and suggest an alternative framework to control coupled ferroic functionalities at the nanoscale.
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Yooun
authors.initials: Y
authors.lastname: Heo
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Songbai
authors.initials: S
authors.lastname: Hu
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Sharma
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Kwang-Eun
authors.initials: KE
authors.lastname: Kim
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Byung-Kweon
authors.initials: BK
authors.lastname: Jang
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Claudio
authors.initials: C
authors.lastname: Cazorla
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Chan-Ho
authors.initials: CH
authors.lastname: Yang
authors.affiliation: School of Materials Science and Engineering and ‡Integrated Materials Design Centre, University of New South Wales (UNSW) Australia , Sydney, New South Wales 2052, Australia.|Department of Physics and ∥Institute for the NanoCentury, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Jan
authors.identifier: 0000-0003-2814-3241
authors.initials: J
authors.lastname: Seidel
keywords: atomic force microscopy; density functional theory; elastic modulus; ferroelectrics; morphotropic phase boundary; multiferroics; nanostructure