STRUCTURE OF SILICA DETERMINED BY USE OF A LIGHT-SCATTERING METHOD

Electric-light-scattering and centrifugation measurements of normal an d sonicated suspensions containing vapor-phase aggregates of silica sh ow the existence of two types of clusters. The first one is composed f rom smaller and more anisotropic clusters. Their fractal dimension, ob tained from the correlation between electric-light-scattering and cent rifugation data, was 1.8+/-0.1. The second type is composed from the b iggest and more isotropic clusters. After sonication the fractal dimen sion of the aggregates rises to 2.3-2.8, which may be related to a pro cess of reorganization accompanying the destruction of the clusters.