A brief review was presented of the concepts regarding the nature of α and β relaxation processes in melts and glasses. Experimental data were used to show that different types of relaxation in oxide systems could be interrelated to each other. The molecular mechanism of viscous flow in inorganic systems was discussed in detail with the use of continuum theories (elasticity and hydrodynamics). A rigorous relationship between the volumes of atoms overcoming the activation barrier, the instantaneous shear modulus, and the barrier itself (free activation energy) was derived. This relationship allowed one to calculate the sizes of atoms involved in the viscous flow with a deviation that did not exceed 10% of the values determined by direct structural methods. In this case, empirically chosen constants were absent. Based upon the results obtained by Anderson and Stewart (1954) and Nemilov (1974), it was established that the activation energy for ionic conduction could be calculated using similar notions. It was demonstrated for the first time that the universal relation between the viscosity and conductivity over a wide range of temperatures (for alkali-containing oxide melts) i.e., the Littleton equation, finds a simple quantitative explanation in the framework of the same models, even though the mechanisms of both processes do not depend upon each other.

Relaxation Processes in Inorganic Melts and Glasses: an Elastic Continuum Model as a Promising Basis for the Description of the Viscosity and Electrical Conductivity. S.V.Nemilov: Glass Physics and Chemistry, 2010, 36[3], 253-85