Synthesis of GeO2-doped SiO2 aerogels and xerogels

This work describes a new rapid method for preparation by sol-gel method of GeO2-SiO2 glass with GeO2 doping level varied from 0 to 10 mol%. From the same wet gels, both aerogels and xerogels were synthesized and different thermal treatments were performed in order to obtain the corresponding glasses. Bulk glasses were obtained by the aerogel route that is shown to be the most convenient method in terms of time saving. Instrumental neutron activation analysis (INAA) was employed to determine germanium concentration in the gels. Inductively coupled plasma mass spectroscopy (ICP-MS) was utilized to check the composition of the gels used as precursors for optical glasses. The porosity of both aerogels and xerogels was measured by adsorption isotherms. Solid-state Si-29 nuclear magnetic resonance at the magic angle (Si-29 MAS-NMR) was employed to characterize the local bonding structure in both gels and glasses. (C) 2002 Elsevier Science B.V. All rights reserved.