Coloration Behavior and Variation in Thermal Properties of Ag-Doped Glasses Prepared by Ion-Exchange
Yusuke NOMIYA, Naoto KOBAYASHI, Takashi WAKASUGI, Junji NISHII and Kohei KADONO
Abstract:It has been reported that a sub-wavelength structure can be formed at the surface of glass, into which silver ions are incorporated through ion-exchange, by means of imprint molding at a lower temperature than softening temperature of the glass. In order to apply this technique to practical glass systems used in mold processing, we investigated ion-exchange behaviors, variation in softening temperature and optical transmission spectra after the ion-exchange and post-heat-treatment for various kinds of glasses. The results were discussed from the viewpoint of the glass composition and structure. The investigated glasses were soda-lime silicate, aluminosilicate, borosilicate, aluminoborosilicate, and fluoroaluminoborosilicate glasses. The amount of incorporated silver at the same ion-exchange condition was the highest for the aluminosilicate glass, and decreased in the order of aluminoborosilicate, soda-lime silicate, borosilicate, and fluoroaluminoborosilicate glasses. The lowering rate of softening temperature had a good correlation with the ion-exchange rate, I.e., molar fraction of Ag to total monovalent ions at the glass surface. For aluminosilicate and aluminoborosilicate glasses having no or little non-bridging oxygen, no coloration was occurred after the ion-exchange and post-heat-treatment although the absorption edge at the short wavelength side shifted to the near ultra violet region. Whereas the fluoride ions in fluoroaluminoborosilicate glass hindered the ion-exchange, they suppressed the reduction of Ag+ ions and the red-shift of the absorption edge. Key Words:Ion-exchange, Softening temperature, Non-bridging oxygen, Nanoparticle, Molding, Nano-imprint, Microlens array, Aspherical lens, Sub-wavelength structure