Fabrication and microstructure of SiO₂−GeO₂ sol-gel glass coatings

Abstract

SiO₂−GeO₂ sols and gel glass coatings with different contents of germanium dioxide were fabricated. Stable and transparent sols could only be obtained when the content of GeO₂ was under 35%. It is shown by SEM that only one continuous phase is observed in the coating of 65SiO₂·35GeO₂ and plenty of Ge, O and Si were all found in it. However, the separated phase is found in the coating of 60SiO₂·40GeO₂ and a large number of Ge and O. It is proved by the Raman scattering investigation that the separated phase in the coating of 60SiO₂ ·40GeO₂ is germanium dioxide. The congeries of hydrolystates of Cl₃ GeCH₂ CH₂ COOH play the main role in the formation of the separated phase when the proportion of GeO₂ is much higher. Si−O−Ge, Si−O−Si, and Ge−O−Ge bonds form in the coating of 65SiO₂·35GeO₂ and this coating is homogenous.

Keywords

SiO₂−GeO₂ / sol-gel / eoating / microstructure

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