Abstract
The effects of oxygen vacancies and their migrations on the dielectric responses of pure BaTiO3 (BT) ceramics and (Ba0.9Ca0.1)1.01(Ti0.9Zr0.1)O3 (BCTZ) ceramics, where portions of Ba and Ti were respectively substituted with Ca and Zr, were studied using wideband dielectric spectroscopy. The decrease in the dipole polarization of BT ceramics after annealing in a reducing atmosphere was due to domain-wall clamping by oxygen vacancies, while that of ionic polarization was attributable to lattice hardening by the incorporation of oxygen vacancies into the BT lattices. The dipole polarization of BCTZ ceramics indicated the same change as did that of BT ceramics after annealing, but the ionic polarization was independent of PO2 in annealing because of the anti-reducing behavior of BCTZ ceramics. The oxygen vacancy migration in BCTZ ceramics could be detected as a change of wideband dielectric spectra. The change observed only in the dipole polarization could be explained the oxygen vacancy migration from the anode to the cathode.