A simplified model on bound dipoles explaining anomalous temperature dependence of dielectric relaxation amplitude

Abstract Normally dielectric relaxation amplitude increases as the temperature decreases. However, certain materials, such as hydrated systems and carboxylic acids, exhibit the opposite manner: i.e. the dielectric relaxation amplitude decreases with decreasing temperature. To elucidate the physical mechanism underlying this phenomenon, a simplified model consisting of a host material and surrounding small solvent molecules that bind to the host surface with a certain probability determined by the binding free energy is considered. This model is solved analytically, yielding a representation of the dielectric amplitude that follows an Arrhenius type behavior in the low temperature limit. This temperature dependence arises from the formation of antiparallel correlations between the dipole moments of solvent molecules due to geometric constraints imposed by the host. It is demonstrated that reported anomalous temperature dependence observed in hydrated proteins, hydrated lithium ions, and acetic acids can be reproduced using this model. Consequently, the universality of this type of the temperature dependence is proposed.