Composition fluctuation in an alkali silicate glass

Abstract

Inclination toward composition fluctuation was assumed to be an inherent property of silicate glasses. An alkali silicate glass of the system Li2O-Na2O-SiO2 chosen for investigation was broken into small grain sizes from 10^-5 to 10^-2 g and then separated into various fractions by sieving. A certain number of grains of different mass were analyzed with respect to the oxide composition. The analytical investigations proved that the lithium and sodium ions were mixed to a high extent and that the scattering of the mole fractions of the alkali ions obeys the Gaussian distribution. Clear evidence was found for partial segregation of the silica and the alkali oxides. No grain was found with relatively high mass and relatively low silica content. On the basis of the scattering of the mole fractions of the silica and the alkali ions in the grains the relative frequency (distribution density) was calculated and presented by contour and perspective diagrams in dependence on the mass of the grains.The influence of the melting procedure on the fluctuations of the glass composition was not investigated.A correlation between the inhomogeneity of the glass and its fragility is assumed.