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Article Dans Une Revue Chemistry of Materials Année : 2020

Perovskite-Type CuNbO3 Exhibiting Unusual Noncollinear Ferrielectric to Collinear Ferroelectric Dipole Order Transition

Résumé

We report a perovskite oxide with a new type of polar structure, CuNbO3, thanks to the use of high-pressure and high-temperature synthesis. The perovskite-type CuNbO3 was previously obtained under high-pressure and high-temperature conditions, but its crystal structure has not been solved yet. Our structural analysis reveals that CuNbO3 perovskite crystallizes in a polar monoclinic space group (Pc) with a root 2 a(pc) x root 2 a(pc ) x 2a(pc) unit cell (a(pc) being the pseudo-cubic lattice parameter), which VT, is one maximal nonisomorphic subgroup of the polar rhombohedral space group, R3c. This compound exhibits a remarkable "noncollinear ferrielectric" structure due to parallel displacements of Cu+ and antiparallel displacements of Nb5+ along different axes, representing a new type of polar phase in the perovskite structure. We also observe that the noncollinear ferrielectric Pc s tructure transforms around 470 K into the collinear ferroelectric R3c structure that features parallel displacements of Cu+ and Nb5+ in the same direction. The present work extends the accessible composition range of the perovskite niobate series and demonstrates the role of A-O covalency in determining their crystal structures.

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Chimie Matériaux
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Dates et versions

hal-02928566 , version 1 (09-09-2020)

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Masayuki Fukuda, Ikuya Yamada, Hidenobu Murata, Hajime Hojo, Olivier J. Hernandez, et al.. Perovskite-Type CuNbO3 Exhibiting Unusual Noncollinear Ferrielectric to Collinear Ferroelectric Dipole Order Transition. Chemistry of Materials, 2020, 32 (12), pp.5016-5027. ⟨10.1021/acs.chemmater.0c00444⟩. ⟨hal-02928566⟩
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