Ferroic characterizations, phase transformation, and internal bias field in 0.75Pb(Fe2/3W1/3)O3–0.25PbTiO3 multiferroic ceramic

The complex perovskite of 0.75Pb(Fe2/3W1/3)O3–0.25PbTiO3 (0.75PFW-0.25PT) ceramic was prepared by the conventional oxide mixing method. The detailed microstructure of 0.75PFW-0.25PT ceramic was investigated. At room temperature, the TEM analysis reveals that only cubic structure (nonpolar) exists, which is different from the phase coexistence of cubic (66%) and tetragonal (34%) structure revealed by XRD. A mechanism dominated by a temperature rise due to electron-beam irradiation has been proposed. The XPS measurement confirms the mixed balance state of Fe2+ and Fe3+ in the as-prepared 0.75PFW-0.25PT specimen, which facilitates the formation of the defect dipoles with oxygen vacancies, in turn resulting in the internal-bias field (Ei) phenomenon. The appearance of weak magnetic interactions is believed relating to the presence of noncompensated magnetic moments in Fe-rich islands. These results provide key information for understanding the composition, defect, ferroelectric, and ferromagnetic properties in 0.75PFW-0.25PT ceramic.