Precurrent and dielectric breakdown in titania ceramics - Critical current

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