On the origin of time-temperature superposition in disordered solids

In this paper by employing various experimental facts for different classes of materials, two critical conditions are derived, which lead to the empirically used scaling relations describing the ac response of disordered nonmetals. In parallel the origin of time-temperature superposition is explored while the scenario of time-pressure (or /temperature) superposition is introduced. Moreover, a unified equation for the entire frequency range of ac conductivity is proposed. The results are physically visualized within the frame of percolation theory, attempting to establish a link to the dominant approaches of Hunt [ Philos. Mag. B 81 , 875 ( 2001 )] and Dyre [ J. Appl. Phys. 64 , 2456 ( 1988 )] .