Hybrid improper ferroelectricity in La2Sr (Sc1−xFex)2O7 ceramics with double-layered Ruddlesden–Popper structures.

Numerous hybrid improper ferroelectrics have been discovered in bulk oxides with layered perovskite structures. In contrast, the competition between the interlayer rumpling and oxygen octahedral rotation suppresses the ferroelectricity in layered perovskite material with trivalent cation at the B-site. In the present work, single-phase dense La₂Sr(Sc_1−xFe_x)₂O₇ ceramics with double-layered Ruddlesden–Popper structures have been prepared, and room-temperature ferroelectricity is discovered in the ceramics with x ≤ 0.10. The ferroelectric polarization and coercive field decrease with increasing content of Fe³⁺ cations, consistent with the decline of oxygen octahedral rotation and tilting angles. Although the linear relationship between the Curie temperature and the tolerance factor for La₂Sr(Sc_1−xFe_x)₂O₇ ceramics is established, the line is far away from that for A²⁺₃B⁴⁺₂O₇ ceramics due to the large interlayer rumpling in the present ceramics. Although no single-phase multiferroic has been discovered in this work, an effective way to introduce magnetism into hybrid improper ferroelectric is provided. [ABSTRACT FROM AUTHOR]