Dielectric Breakdown Mechanism of Perovskite-Structured Ceramics

We precisely measured the dielectric breakdown strength of SrTiO3, CaTiO3, and CaZrO3 ceramics as a function of temperature, and revealed the dielectric breakdown mechanism of the ceramics. For the dielectric breakdown test, ceramics specimens with a lot of round-bottom holes were prepared. Using the specimens, the breakdown positions were stabilized and a reliability of breakdown strength was improved as well as the measurement efficiency. As a result of the dielectric breakdown tests, it was found that the dielectric breakdown strength decreased with increasing permittivity at room temperature and the permittivity dependence of breakdown strength obeyed Griffith type energy release rate model. At high temperature above 100ºC, the dielectric breakdown mechanism of SrTiO3 and CaTiO3 ceramics was explained by an intrinsic breakdown model. In contrast, an intrinsic dielectric breakdown of CaZrO3 ceramics didn't occur in the measurement temperature range up to 210ºC. To obtain a high dielectric breakdown strength at high temperature, the dielectric permittivity is required to be low to some extent and the defect concentration of oxygen vacancies should be minimized in the perovskite-structured oxide.