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Enhanced hybrid improper ferroelectricity in Fe/Nb cosubstituted Ca 3 Mn 2 O 7 ceramics
Author(s) -
Chen Bu Hang,
Sun Tu Lai,
Wei Li Yu,
Liu Xiao Qiang,
Wen Wen,
Tian He,
Li Jiang Yu,
Chen Xiang Ming
Publication year - 2021
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17791
Subject(s) - ferroelectricity , octahedron , polarization (electrochemistry) , materials science , phase transition , oxygen , condensed matter physics , ceramic , crystallography , transition temperature , crystal structure , chemistry , optoelectronics , dielectric , physics , composite material , superconductivity , organic chemistry
Abstract The prototypical Ruddlesden‐Popper compound Ca 3 Mn 2 O 7 has been predicted to possess hybrid improper ferroelectricity, where the polarization is induced by the condensation of two oxygen octahedral distortion modes. Nevertheless, it is a big challenge to switch the polarization at room temperature in Ca 3 Mn 2 O 7 since the presence of intermediate nonpolar Acaa phase generally leads to the complex domain morphology. Here, the effects of Fe/Nb cosubstitution on hybrid improper ferroelectricity in Ca 3 Mn 2 O 7 are reported, and easy polarization switching at room temperature is achieved in Ca 3 [Mn 0.5 (Fe 0.5 Nb 0.5 ) 0.5 ] 2 O 7 . The ferroelectric phase transition occurs directly from I 4/ mmm to A 2 1 am at a temperature far above room temperature without intermediate nonpolar Acaa phase. The distinct transition pathway forms the alternating 180°‐type ferroelectric domains rather than the irregular 90°‐type ferroelastic domains stacked along [001], resulting in easy polarization switching at room temperature. Moreover the enhanced ferroelectric polarization ( P r ~2.0 μC/cm 2 ) is obtained due to the increased anti‐ferrodistortive displacements of Ca cations at A ‐site, arising from the larger amplitudes of oxygen octahedral distortions. Chemical pressure is emphasized here for the tunability of phase transition, domain morphology, and ferroelectric characteristics, and it provides a useful approach for designing and creating high‐performance improper ferroelectrics.