Inhibition of Oxygen Vacancy Derived from Donor Doping in Relaxor Ferroelectric Films for Improving Dielectric Energy Storage

The defect carriers in most dielectric capacitors always reduce the breakdown electric field and polarization, thereby limiting the improvement of energy storage performances. This work proposes a strategy of donor doping in P-type leakage conductance relaxor ferroelectric films to depress the oxygen vacancies, with Fe3+ substituting for Mg2+ in SrBi4LaMg0.5Ti4.5O18 film capacitors. It is shown that the introduction of Fe3+ effectively inhibits the generation of oxygen vacancy, and the decrease of the oxygen vacancy concentration reduces the p-type leakage conductance and thus increases the breakdown strength of the film capacitors. The reduction of oxygen vacancy also weakens the limitation of the domain wall pinning effect on the polarization of the materials. This regulation effectively breaks through the unfavorable coupling between the breakdown electric field and polarization. An optimum energy storage density of 116.7 J/cm3 and energy efficiency of 74% were obtained in SrBi4LaMg0.5–xTi4.5O18:xFe films. This work provides an important alternative to regulate the oxygen vacancy generation and improve the energy storage performances of dielectric film capacitors.