ELECTRICAL BREAKDOWN OF THE POSITIVE TEMPERATURE-COEFFICIENT OF RESISTIVITY BARIUM-TITANATE CERAMICS

Positive temperature coefficient of resistivity barium titanate cerami c is a semiconductor at room temperature, so it is self-heated under c ertain applied voltage, and then changes into an insulator. The electr ical breakdown has been investigated with the resistance-temperature c haracteristics of the three samples which have different compositions. The grain size effect on the breakdown voltage also is discussed. As the applied voltage increased, the electrical breakdown was initiated when the specimen interior was heated above the temperature correspond ing to the maximum resistance on the resistance-temperature curves by joule heat.