Analysis of the DC breakdown in sintered titanates

The electrical breakdown in a dielectric medium may be defined as the state when the conductivity increases as a function of time without limit under the influence of a constant electric field. In solids, if the mechanical breakdown due to electromechanical coupling is unimportant, such increase in the conductivity-leads to the so called thermal breakdown. In inhomogeneous solids the breakdown condition is governed by the maximum local conductivity which may include gaseous discharge in the pores, the higher conductivity of the grain boundary relative to the bulk, etc. If one mechanism causes the maximum local conductivity, then the characteristics, such as the temperature and density dependences, of the breakdown condition due to this mechanism could be observed, and vice versa.