Dielectric and Ferroelectric Response of Multiphase Bi-Fe-O Ceramics

The structural, dielectric, and ferroelectric characterization of multiphase Bi-Fe-O prepared with an excess of Bi up to 20% is reported. It is found that the dominant phase in all samples is the BiFeO3 perovskite in addition to an increasing amount of the Bi-rich sillenite phases (Bi12.5Fe0.5O19.48/Bi25FeO39) with the Bi excess content. At room temperature, the multiphase Bi-Fe-O results in advanced electrical properties, with higher dielectric constant (161 at 1 MHz) and low losses (tan delta = 0.032 at 1 MHz). The ferroelectric character of multiphase ceramics is confirmed by PUND measurements, which shows increased polarization values and coercive field with respect to the single phase ceramics.