Effect of Acceptor (Mg) Concentration on the Resistance Degradation Behavior in Acceptor (Mg)‐Doped BaTiO ₃ Bulk Ceramics: II. Thermally Stimulated Depolarization Current Analysis

Abstract

Thermally stimulated depolarization current (TSDC) of acceptor (Mg)‐doped BaTiO 3 ceramics was analyzed with different acceptor concentrations for coarse‐grained specimens with uniform grain sizes. In all specimens, the increase of the polarization temperature ( T P ) for a fixed condition of polarization field ( E P ) and polarization time ( t P ) increased TSDC peak associated with an oxygen vacancy ( V O •• ) relaxation. When the acceptor concentration is increased, both T P to generate same magnitude of TSDC and the relaxation temperature ( T m ) of the TSDC peak systematically decreased. On the other hand, the activation energy of the oxygen vacancy relaxation showed roughly constant values of ∼0.9 eV, irrespective of acceptor concentration. Such behavior can be explained by a decrease in the relaxation time constant (τ 0 ), which is in turn associated with the shape of oxygen vacancy profile in the specimen after polarization. The decrease of T P , T m , τ 0 , and the little change of activation energy from the TSDC data with the increase of acceptor concentration implies an increase in the oxygen vacancy concentration C ( V O •• ). The experimentally observed behavior of C ( V O •• ) vs acceptor concentration could be explained by the defect chemical model, and from these results, the acceptor ionization energy E A was estimated to be about 1.0 eV.