Electric field concentration in the vicinity of the interface between anode and degraded BaTiO3-based ceramics in multilayer ceramic capacitor

The electric field distribution of degraded dielectric layers in multilayer ceramic capacitors (MLCCs) was investigated by Kelvin probe force microscopy (KFM) to clarify the insulation degradation mechanism in MLCCs. For the degraded dielectric layers, the electric field was found to be concentrated near the anodes. This concentration easily moved to the opposite side with a reversal of the applied voltage of 5 V (13 kV/cm) during KFM measurement at room temperature. On the other hand, electric field concentrations and electric field distributions did not change in fresh MLCCs, indicating that the electric field concentrations easily transfer near higher-potential interfaces between electrodes and ceramics only in degraded MLCCs. These facts suggest that Schottky barriers would be formed in degraded MLCCs. The KFM technique discussed in this work is a very useful tool for measuring the surface potential and helps clarify the local electric field concentration near the electrodes.

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