Precurrent and dielectric breakdown in titania ceramics - Critical current

Dielectric breakdown of titania ceramics was investigated with respect to the precurrent which is the current flow before breakdown. The precurrent behavior can be divided into two regions; an electron multiplication region in which carrier electron increases with a constant rate and a critical current increase just before the breakdown. Optical microscopic observation indicated that a part of titania ceramics melted during dielectric breakdown. Relation between critical current and applied electric field, as well as the electric power and heat calculated from the critical current, supported the observed melt of titania ceramics.