Dependence of the breakdown strength on thickness and permittivity

The dielectric breakdown strengths of Al₂O₃ and BaTiO₃ ceramics have been investigated in terms of thickness and permittivity dependence. From the obtained results, it is possible to define a thickness dependent breakdown strength regime. For bulk samples it will be shown, that the breakdown strength is inversely proportional to the permittivity. Furthermore space charge limited conduction (SCLC) can be identified as dominating conduction mechanism in Al₂O₃ and BaTiO₃ ceramics. Based on the experimental findings a recently developed Griffith type energy release rate model for tubular channels can be applied [1].