Dielectric small-signal response by protons in amorphous insulators

A model is proposed in which protons fluctuate between neighboring atomic shells either by thermal activation or by a tunneling process. The transition probability of the protons depends on the distance between the adjacent atoms. The characteristic pair distribution function of interatomic distances in the amorphous state is a consequence of locally minimizing the potential energy of the atoms during condensation, as has been shown by F.F. Abraham (1980). This general principle of minimizing the energy leads to similar distribution functions in different materials. Therefore, different types of insulators have a similar relaxational behavior. Experiments carried out with thin films of aluminum oxide and polyimide confirm quantitatively the proposed model.>