Thermal Expansion, Composition and Structure of Glass—PART I

Abstract

Thermal expansion and composition of glass are correlated by the equation: α = Σ a_i c_i, a_i being the additive constant for the ith oxide and c_i the concentration of the ith oxide in gms per cc. of glass. The additive factors for the alkali oxides, alkaline-earth oxides, MnO, ZnO, PbO, BaO, B₂O₃, Al₂O₃, SiO₂ and TiO₂ have been evaluated.

The factors due to silica and the alkali oxides take three different sets of values depending on the ratio, (non-bridging oxygen): (silicon) in glass being (i) less than 0.5, (ii) between 0.5 to 1.0, and (iii) greater than 1.0. For other oxides only one set of factors holds good for all the compositions. The equation has been shown to be useful for calculating thermal expansion of a wide variety of glasses.