SANS of ZrO 2·SiO 2 gels

Abstract

Small angle neutron scattering (SANS) measurements have been performed to investigate the nanoscale structure of materials of the system xZrO 2·SiO 2 with x≤10 mol%, at different processing stages. The materials were prepared by sol–gel using the alkoxides method, in strong acidic conditions. Samples studied as xerogels were heat-treated at 120° C and 850° C; as wet gels at the gel point; and after 4 h aging at 60° C. The samples showed extended linear chains ca. 10 nm long at the gel point. The aged gel has a mass fractal structure with fractal dimension of ca. 1.8. The 120°C heat-treated xerogel shows homogeneous oxide regions with 16 nm average diameter and mass fractal nature. For the 850°C heat-treated xerogel the oxide regions average diameter reduced to about 13 nm and presented a sharp and smooth surface, obeying the Porod law.