Time Evolution of the Potential Distribution in Earth Alkaline Titanates under de Voltage Stress

Earth alkaline titanates which are commonly used as dielectrics in ceramic capacitors may exhibit a long‐term degradation of the insulation resistance under simultaneous dc field and temperature stress. In order to study the nature of this process, it is necessary to detect the time evolution of the potential distribution between anode and cathode. A method is introduced which allows the determination of the potential distribution by the electrostatic deflection of an electron beam close to the edge of a current‐carrying sample. The results are used to evaluate various models which have been proposed to explain the mechanism of the degradation process.