Cobalt-Substituted Seven-Layer Aurivillius Bi8Fe4Ti3O24 Ceramics: Enhanced Ferromagnetism and Ferroelectricity

In this work, Aurivillius-phase Bi8Fe4-xCoxTi3O24 (7-BFCT, 0 ≤ x ≤ 0.4) powders and ceramics were successfully prepared by the combination of citrate combustion and hot-press methods. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) indicate a successful synthesis of the pure phase of the 7-BFCT ceramics, and all the samples showed a good seven-layer structure of the Aurivillius phase. Partial Fe substituted by Co was found to be effective to enhance both ferromagnetic and ferroelectric properties at room temperature, and the largest remnant magnetization (2Mr) of ~0.69 emu/g was revealed at the composition of x = 0.4. Zero field cooling and field cooling (ZFC-FC) magnetization measurement confirmed its magnetic transition occurring at a high temperature of ~750 K. Correspondingly, the enhanced ferroelectric properties of such Co-substituted ceramics were also investigated.