Investigation on dependence of BiFeO₃ dielectric property on oxygen content

The influence of oxygen content on the dielectric property of BiFeO₃ ceramics is studied by experiment and first-principles calculation. The experimental result demonstrates that the dielectric constant of BiFeO₃ is strongly dependent on introduced oxygen and oxygen vacancies. By comparison with BiFeO₃, the introduced oxygen and oxygen vacancies can lead to a reduction in dielectric constant of BiFeO_\delta at a lower frequency. The first-principles calculation also shows a similar result when photon energy is in a range of 2.0—4.1 eV. A likely explanation is that this oxygen content dependence may be ascribed to the distortion of Fe—O octahedron structure due to oxygen vacancies or excess oxygen ions in the crystal structure of BiFeO₃.