Relaxation and Diffusion Dynamic and Thermodynamic Properties in Amorphous Materials are Universal

Abstract

The physical structures and chemical compositions and bonds of amorphous materials in the liquid and the glassy state are extremely diverse even confined with a specific class. Therefore, it would be incredible if someone ever suggests the relaxation and diffusion properties of amorphous materials are universal. Nevertheless, the eminent condensed matter physicist P.W. Anderson did just that. As cited by the editors in their call for papers of this themed collection on Amorphous Materials, Anderson once observed that “Randomness and disorder could result in generic properties that are utterly different from those of merely somewhat impure regular materials”. His observation was not baseless because previously the existence of universality was anticipated in a theory of relaxation and diffusion based on classical chaos published by the present author in 1979. Since then, experimental data and simulation results collected in widely different amorphous materials over the past 47 years have provided indisputable evidences of the universal properties as predicted by the theory, currently known as the Coupling Model (CM). Part of the findings prior to 2022 have been reviewed in Prog. Mater. Sci. 2023, 139, 101130. The current review is focused on the new data emerging after 2022 as well as relevant older data not considered before. Altogether, the evidences extracted from the data reaffirm the universality of relaxation and diffusion in diverse amorphous materials in accord with the predictions of the CM.