Ubiquity of the kinetic compensation effect: A consequence of the existence of a maximum in energy dissipation

Abstract

The significance of the often observed kinetic compensation effect (KCE) remains controversial. The assumption of its validity, as well as its ubiquity, has led to speculations on its significance with no general consensus in the scientific community. Efforts to understand the KCE have usually attempted connections between microscopic events, structures, and mechanisms involved in various kinetic processes. An alternative proposition, with no relation to specific mechanisms, is presented suggesting that there is no new conceptual physics in the KCE. An analysis of internal friction (IF) in the framework of linear response to weak perturbations highlights that the concomitant energy dissipation cannot exceed a maximum or peak value which depends solely on the anelastic properties of the material. The KCE is shown to be a consequence of this simple fact. This physical principle underpinning the KCE is able to explain its ubiquity because of its general nature beyond any specific kinetic rate mechanism. Examples of IF in different systems such as polycrystalline thermoelectric composites and Al bicrystals, which show evidence of the KCE, conform to this prediction. While the observation on Al bicrystals has previously been presented and interpreted as signaling a phase transition, the analysis presented here demonstrates the simpler alternative. A similar argument is presented to derive the KCE in the thermal desorption of gases, which involves kinetic processes unrelated to the above examples. It is proposed that a KCE can, in general, be deduced for any set of closely related relaxation processes having close peak values of energy dissipation.