The Mechanism Of Viscous Flow In Glasses

The viscous flow of inorganic glasses is considered from the point of view of valence theory and free-volume theory. It is shown that the "hole formation" corresponds to local fluctuation deformation of the glass network and the "transition of a particle into a micro-cavity," to the switching of the bridging atoms. A possible refinement of the valence theory of flow is discussed; this is based on the assumption that in silicate glasses there are oxygen atoms with vacant bonds.