Weakening Effect of Mn on the Oxygen Vacancies of KNN-BZT-Mn Ceramic with Improved Energy Storage Performance

Abstract

In this work, the weakened pinning effect of oxygen vacancies due to the introduction of Mn on the transfer from polarization nanoregions to normal ferroelectric domains is investigated through the component design. Therefore, the 0.85K0.5Na0.5NbO3−0.15Bi0.5Zn0.5Ti0.5O3-x mol% MnO2 (abbreviated with KNN- BZT-xMn, x = 0 and 0.1, i.e. KNN-BZT and KNN-BZT-Mn) ceramics were synthesized by the conventional solid-reaction method. The relaxor transition from ferroelectric R to paraelectric C phase of the ceramics is demonstrated by the temperature-dependent dielectric constants. The oxygen vacancies account for grain polarization and grain boundary polarization is derived from the migration of oxygen vacancies to the grain boundary, which is indicated by the complex impedance spectra and slimmer ferroelectric hysteresis loop for KNN-BZT-Mn. The mechanism for enhanced energy storage performance is ascribed to the NbMn-Vo decreases the pinning effect of the oxygen vacancies.