Intrinsic Mechanisms of Multi-Layer Ceramic Capacitor Failure.
Annual rept. 15 Mar 85-14 Mar 86,
VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG COLL OF ENGINEERING
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It has been established that the dominant charge carrier of leakage current in the BaTi03 based X7R ceramic that we have measured is the electron. Galvanic cell measurements yield oxygen ion transport numbers of essentially zero. The major effect of oxygen movement is not ionic current, but degradation. A generic degradation current-time curve is discussed. Two models for leakage current vs time are presented one based on oxygen vacancy and conduction electron increase the other on grain boundary barrier height reduction. Both predict exponential or near-exponential increase of leakage current with time, which has been reported. Reasons for the decrease in activation energy with degradation are discussed. This is attributed to decrease in polaron hopping or grain boundary potentials, or both.
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- Solid State Physics