Hybrid improper ferroelectricity and complex phase evolution in Eu2SrSc2O7 ceramics

Abstract

Hybrid improper ferroelectricity (HIF) in double-layered Ruddlesden–Popper oxides has been widely studied in recent years. In the present work, the complex phase transition sequence in Eu2SrSc2O7 ceramics has been discovered by temperature-dependent dielectric response and in situ synchrotron x-ray diffraction measurements. Upon heating, the ceramic exhibits two successive first-order phase transitions, evolving from a room-temperature ferroelectric A21am phase to an intermediate ferroelectric P21am phase around 760 K and ultimately to a paraelectric Amam phase above 900 K. The intrinsic nature of the room-temperature ferroelectricity is confirmed by the well-defined electric polarization–field hysteresis loops and distinct switching current peaks, revealing a large remanent polarization of approximately 3.6 μC/cm2. These results not only clarify the intricate structural evolution in Eu2SrSc2O7 ceramics but also highlight a promising pathway for the rational design of HIF materials with robust ferroelectric performance.