Relaxation behavior of oxygen vacancies in Sc-doped BaTiO3

Abstract

The dielectric properties of the Ba(Ti1-x Sc x )O3-δ system have been studied as functions of the temperature and the frequency for x = 0.0005 to 0.05. The dielectric loss (tanδ) peak shifted to higher frequency with increasing Sc content, and the loss peak moved to higher frequency with increasing temperature, showing a thermally- activated process. Such a behavior was in good agreement with Debye’s equation. Two activation energies were estimated at Sc ≤ 1 mol% whereas a single activation energy was determined for x = 0.02 and 0.05 on the temperature range studied. At Sc ≤ 1 mol%, the activation energy at higher temperatures could be due to the dissociation of the defect complex (Sc’ Ti –V o) and to the swing motion of oxygen vacancies. The single activation energy at Sc ≥ 2 mol% implies that over the temperature range studied, the relaxation mechanism could be due to the reorientation of a dipolar complex without any oxygen vacancy dissociation.