The breakdown phenomenon and mechanism of BaTiO/sub 3/-CaSnO/sub 3/-CaTiSiO/sub 5/ (BCC) ferroelectric ceramics, which have a special grain-core-grain-shell microstructure, are investigated. The relation of current I vs. electrical intensity E of BCC ferroelectric ceramics is found to exhibit a four-region characteristic. When an electric field weaker than 2 kV/mm is applied (region I), a conduction current of 10/sup -8/ A is obtained. The leakage current then increases linearly with increasing voltage up to 5 kV/mm in an ohmic manner (region II) within 10/sup -6/ A. Region III is a saturation region, in which the current remains constant while the electric field increased to 7 kV/mm. For voltages still higher (region IV), the current begins to rise steeply, resulting in the occurrence of breakdown through weaker zones, until a negative resistance region begins, with the simultaneous destruction of the entire specimen caused by thermal explosion.
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