The physical mechanisms of relaxation times distribution in inorganic and organic disordered ferroelectrics

Abstract

We discuss the physical background for relaxation times distribution in organic and inorganic disordered ferroelectrics. We show that such background is a disorder which is believed to be a reason for relaxor behavior. Due to this disorder the internal electric and elastic fields are of a random nature being characterized by certain distribution function. Having the distribution function f(E) of random field E, we can obtain the distribution function of relaxation times F(τ) with the help of relation between τ and E. Latter relation can be obtained considering the dynamics of a single electric dipole in a random field created by the ensemble of defects and impurities in a sample. We show that in our approach the known empirical relaxation laws like Cole–Cole, Davidson–Cole, Havriliak–Negami etc correspond to different concentrations and kind of defects in the above substances. The character of interaction between them also plays an important role. The comparison of our theory with experiment shows that our approach captures the main relaxation properties of disordered ferroelectrics. Our formalism can be easily generalized on the other nonferroelectric disordered substances, both organic and inorganic.