Oxygen-vacancy-mediated dielectric property in perovskite Eu_0.5Ba_0.5TiO_3-δ epitaxial thin films

Dielectric relaxation in ABO₃ perovskite oxides can result from many different charge carrier-related phenomena. Despite a strong understanding of dielectric relaxations, a detailed investigation of the relationship between the content of oxygen vacancies (V_O) and dielectric relaxation has not been performed in perovskite oxide films. In this work, we report a systematic investigation of the influence of the V_O concentration on the dielectric relaxation of Eu_0.5Ba_0.5TiO_3-δ epitaxial thin films. Nuclear resonance backscattering spectrometry was used to directly measure the oxygen concentration in Eu_0.5Ba_0.5TiO_3-δ films. We found that dipolar defects created by V_O interact with the off-centered Ti ions, which results in the dielectric relaxation in Eu_0.5Ba_0.5TiO_3-δ films. Activation energy gradually increases with the increasing content of V_O. The present work significantly extends our understanding of relaxation properties in oxide films.