Origin of Ferroelectricity in a Family of Polar Oxides: The Dion鈥擩acobson Phases
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- 作者：Nicole A. Benedek
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：April 7, 2014
- 年：2014
- 卷：53
- 期：7
- 页码：3769-3777
- 全文大小：387K
- 年卷期：v.53,no.7(April 7, 2014)
- ISSN：1520-510X
文摘
Recent work on layered perovskites has established the group theoretical guidelines under which a combination of octahedral distortions and cation ordering can break inversion symmetry, leading to polar structures. The microscopic mechanism of this form of ferroelectricity鈥攕o-called hybrid-improper ferroelectricity鈥攈as been elucidated in two families of layered perovskites: AA鈥睟2O6 double perovskites and Ruddlesden鈥揚opper phases. In this work, we use symmetry principles, crystal chemical models, and first-principles calculations to unravel the crystal chemical origin of ferroelectricity in the Dion鈥揓acobson phases, and show that the hybrid improper mechanism can provide a unifying explanation for the emergence of polar structures in this family of materials. We link trends in the magnitude of the induced polarizations to changes in structure and composition and discuss possible phase-transition scenarios. Our results suggest that the structures of several Dion鈥揓acobson phases that have previously been characterized as centrosymmetric should be re-examined. Our work adds new richness to theories of how polar structures emerge in layered perovskites.