Evolution of the dielectric response during the degradation of Mn-doped BaTiO/sub 3/ ceramics measured by impedance spectroscopy

Summary form only given. The degradation process in sintered materials was examined. Low-frequency dispersion measurements of the dielectric constant were performed during the degradation process, that is by holding the samples under DC field at high temperature while the epsilon /sub 1/( omega ) and epsilon /sub 2/( omega ) curves were continuously recorded during about one week. The main results were a relative stability of the epsilon /sub s/- epsilon /sub infinity / dispersion of epsilon /sub 1/( omega ): an increase of omega /sub 2/; and the reappearance of the epsilon /sub 1/ anomaly at T/sub c/ in the samples sintered under low P/sub O2/. The activation energy obtained from the log epsilon /sub 1/ versus 1/T plot seemed to be incompatible with a displacement of oxygen vacancies.<
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