Atomistic Interpretation of the Effect of Composition on the Viscosity of Glass

JSGT 1955 V39 T016-T036

In this paper earlier work on the low-temperature viscosity of simple glasses of widely-different chemical composition is reviewed, and the results are explained on the basis of the properties of ions and their interaction. It was found that a physical picture of the viscous flow of glasses can be obtained only if the interaction of the atoms to a considerable depth is taken into consideration. Among the current approaches to the nature of chemical binding forces, only the concepts of K. Fajans lend themselves to the development of a physical picture of such a "depth-action." This result can be generalised with respect to other mechanical properties of substances as determined by their chemical compositions. The response of matter to mechanical forces must change drastically if the volume under stress decreases below a certain critical value. Viscosity and strength should increase in the same fashion as the surface energy or the adhesion properties if the volume under test becomes too small for a co-operation of atoms over large volumes. This conclusion may be expressed in another form. If a condensed system is subjected to mechanical forces which tend to sever the chemical binding forces between two hypothetical planes of atoms, a large number of adjacent atoms co-operate with the mechanical forces by developing dipole moments, the forces of which aid the separation of the two hypothetical planes.

Evelyn C. Marboe & W. A. Weyl