Self‐Regulated Chemical Substitution in a Highly Strained Perovskite Oxide. (17th March 2022)

• Record Type: Journal Article
• Authors: You, Lu; Wang, Xin; Zhang, Qinghua; Chi, Xiao; Yang, Ping; Hu, Yiqi; Li, Ping; Hui, Qiang; Fang, Liang; Gu, Lin; Xu, Bin; Wang, Junling
• Is Part Of: Advanced functional materials. Volume 32:Number 25(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-17
• Subjects: chemical substitution -- epitaxial strain -- ferroelectrics -- morphotropic phase boundary -- perovskite; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202112463
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Deterministic control of substitution sites is the holy grail of chemical engineering in materials science. The substitution of the dopants in the host crystal lattice usually obeys the empirical Hume‐Rothery rules, in which the mismatch of atomic size must be small and thus site‐specific. Herein, we report an unconventional case of mixed‐site substitution in highly‐strained BiFeO3 thin films. Driven by the delicate balance between chemical strain and epitaxial strain energies, the solid‐solution system demonstrates a self‐regulation behavior in dopant site occupancy to minimize the total free energy. This proposed mechanism offers valuable insight into the chemical substitution pathway in epitaxial thin films and provides a potential route to selectively control the substitution sites. Abstract : Chemical substitution usually follows the empirical Hume–Rothery rules, being site‐specific. Epitaxial strain, however, may tip the energy balance for dopant site selections. In highly‐strain tetragonal‐like BiFeO3, an unusual crossover of site preference occurs when the dopant spans from La ( A ‐site) to Yb (mixed A / B site) in a self‐regulated manner. This effect delivers a potential approach for site‐selective substitution by strain tuning.