The mean polarizability and density of glasses

Abstract

With the combination of the dispersion theory and the Grüneisen constant, the frequency- and density-dependence of the mean polarizability of transparent glasses is discussed. The mean polarizability α is found to be a function of the density ϱ of the glass and the angular frequency ω of the incident light. This function is described by a differential equation of ∂α/ ∂ϱ = −〈 γ〉/ ϱ(2 α + ω∂α/ ∂ω), where 〈γ〉 is the mean Grüneisen constant. At a given frequency of the incident light, the mean polarizability is linearly proportional to the density of the glass. In combination with the Newton-Drude and Lorentz-Lorenz equations, the proposed relationships are used to study the refractive indices of densified SiO 2-glasses.