Thermally stimulated depolarization current (TSDC) of acceptor (Mg)-doped BaTiO3 ceramics was analyzed for submicrometer fine grain specimens. For a fixed condition of polarization field (EP) and polarization time (tP), the TSDC associated with an oxygen vacancy relaxation showed two peaks with relaxation temperatures (Tm) under low polarization temperature (TP) conditions. It is inferred that the TSDC peak of the lower Tm is due to the relaxation of a distributed space charge within a grain and has a short relaxation time constant (0), and the higher Tm is due to the long-range relaxation across grain boundaries with a larger time constant, 0. The onset condition for resistance degradation can be correlated with the breaking point of TP, at which the TSDC peak changes from in-grain relaxation to across-grain boundary relaxation. The breaking point of TP and the time to degradation systematically decreased with the increase of acceptor concentration. Such behavior can be correlated with the decrease of TP, Tm, 0, and little change of activation energy of relaxation, which is due to the increase of concentration.
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Document Type: Research Article
Center for Dielectric Studies, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
MLCC R&D Group, LCR Division, Samsung Electro-Mechanics Co. Ltd., Suwon, Gyunggi-Do 443-743, Korea
Publication date: 01 July 2010