Synthesis of GeO2-doped SiO2 aerogels and xerogels for optical glasses

This work describes a new rapid method for preparation by sol-gel method
of GeO2-SiO2 glass with GeO2 doping levelvaried from 0 to 10 mol%. From
the same wet gels, both aerogels and xerogels were synthesized and
different thermaltreatments were performed in order to obtain the
corresponding glasses. Bulk glasses were obtained by the aerogel route
that isshown to be the most convenient method in terms of time saving.
Instrumental neutron activation analysis (INAA) wasemployed to determine
germanium concentration in the gels. Inductively coupled plasma mass
spectroscopy (ICP-MS) wasutilized to check the composition of the gels
used as precursors for optical glasses. The porosity of both aerogels and
xerogelswas 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.