Early stages in dielectric ageing

We attempt to give a systematic survey from a solid state physics point of view of the relevant electronic, chemical and electrochemical processes in the early stages of dielectric ageing. A first conclusion is that no ageing occurs as long as the dielectric behaves as a dielectric. Ageing always involves a flow of current which by various mechanisms e.g. heating, chemical damage by hot electrons, electrochemical reactions at interfaces weakens the material which then in combination with mechanical and electromechanical forces leads to damage. The crucial processes which have to be understood are the charge flow at points of high local field enhancement and at interfaces and the damage mechanisms resulting from charge flow.