Synthesis and properties of Er3+-doped silica glass by sol-gel processing with organic complexation

Abstract

Er3+-doped silica glass (up to 10 wt%) was synthesized by sol-gel processing with the addition of 3-aminopropyl trimethoxysilane (APS) as a complexing reagent. Er3+ ion reacted with the amino groups and, thus, linked to the silica network during the sol preparation. It is anticipated that the motion of Er3+ ions would be restricted, and the formation of Er3+ clusters inhibited. No detectable phase segregation was observed by means of SEM/TEM, regardless the addition of organic complexing reagent and heat-treatment. Nitrogen adsorption analysis indicated that dense glass was obtained after heating at 900–1000 °C for 10 hrs. Although the current experimental results were not conclusive, both fluorescence spectra and magic-angle spin (MAS) nuclear magnetic resonance (NMR) data were indicative that the addition of the complexing reagent APS might result in a homogeneous dispersion of high level Er3+ doping in the resultant gels. After the removal of organic components, however, Er3+ clustering occurs when firing at a high temperature for a long period of time, e.g. at 1000 °C for 10 hrs, due to enhanced Er3+ diffusion.