Remarkable enhancement in hybrid improper ferroelectricity of Ca3Ti2O7 ceramics by a simple sol-gel process.

• Ca 3 Ti 2 O 7 ceramics were successfully synthesized by a simple tartaric acid sol-gel method. • The remarkably enhanced remnant polarization (4.32 μC/cm2) was achieved. • The sample has the larger antiferroelectric distortion displacements and the larger grain. Ca 3 Ti 2 O 7 with Ruddlesden-Popper structure is a typical hybrid improper ferroelectric with large polarization. But the room-temperature ferroelectricity of Ca 3 Ti 2 O 7 ceramics prepared by a solid-state method is not good enough. In this work, Ca 3 Ti 2 O 7 ceramics with remarkably enhanced hybrid improper ferroelectricity have been successfully fabricated by a simple tartaric acid sol-gel method. The ceramic sample exhibits the highest remnant polarization (4.32 μC/cm2) to our knowledge and lower coercive electric field (108.7 kV/cm) at room temperature. The enhanced ferroelectricity of Ca 3 Ti 2 O 7 ceramics results from the larger antiferroelectric distortion displacements and the larger grain with irregular polygon features. These findings are beneficial for developing room-temperature single phase multiferroic materials with strong magnetoelectric coupling and excellent ferroelectricity. [ABSTRACT FROM AUTHOR]