Structure and dynamics of the opal silica-water system

Abstract

Precious opals are built up from closest-packed silica spheres of about 200 nm diameter. The inelastic neutron scattering by ‘wet’ opal sample with 6 wt% water and by ‘dry’ opal sample 0.8 wt% water was investigated at different temperatures. The comparison between the opal water signal and the ice signal shows substantial differences, indicating a higher density of states in opal water at low frequencies. The silica spheres at low frequencies show a substantially higher density of states than vitreous silica.