The Physical Properties of Glass in Relation to its Structure
JSGT 1946 V30 T031-T053
A fairly extensive account is given of the knowledge we have at present of the structure of glass in general. On this basis some physical properties of glass, viz., the density and the electric conductivity, are discussed in detail. The density of normal glasses can be calculated satisfactorily by means of a formula containing only two constants, both of which have a well-defined physical meaning. One of these constants can give valuable information about the structure of the glass, especially about the way in which the “excess” of oxygen is taken up by the network. The electrical conductivity–temperature relationship is briefly discussed. The two bends in the electrical conductivity–concentration curves in the case of simple sodium glasses are explained. The one at high sodium concentrations (30% Na2O) corresponds to the composition at which oxygen polyhedra with fewer than three bridging oxygen ions begin to occur. The bend at low sodium concentrations (4% Na2O) corresponds to the appearance of so-called “free” sodium ions.
J. M. Stevels
