Microstructure and ferroelectric properties of (Ca1−xSrx)3(Ti1−yMny)2O7 ceramics

Abstract

(Ca1−xSrx)3(Ti1−yMny)2O7 (CSTMO) ceramics with hybrid improper ferroelectricity were prepared by conventional solid-state reaction method. Effect of Sr2+ and Mn4+ contents on microstructure, dielectric and ferroelectric properties have been systematically investigated. The XRD results show that CSTMO ceramics is single phase with orthorhombic structure. The lattice constants and average grain size increase with the increasing of Sr2+ content and decrease with the increasing of Mn4+ content. The introduction of Mn4+ deteriorates the densification of CSTMO ceramics to some extent, and the substitution of Sr2+ with higher content can improve the densification by promoting a rapid interdiffusion movement via grain-boundary. (Ca0.8Sr0.2)3(Ti0.9Mn0.1)2O7 ceramics present the highest dielectric constant and dielectric loss, while the dielectric loss of (Ca0.8Sr0.2)3(Ti0.95Mn0.05)2O7 ceramics has a significant reduction. The leakage current of CSTMO ceramics decreases with the increasing of Sr2+ and Mn4+ content. The leakage behavior suggests that the Ohmic conduction and Schottky emission dominate the leakage current of CSTMO ceramics. Moreover, the remnant polarization decreases with the increasing of Sr2+ because of its suppression for the rotating and tilting angle (a−a−c+) of oxygen octahedron. And the electrical polarization decreases with the increasing of Mn4+ content due to the instability of MnO6 rotation.