State of Silver in Ag2O-B2O3-Al2O3 Glass and Its Change by Heat Treatment
Takashi WAKASUGI, Atsushi KOTANI, Teppei KATSUMATA, Katsuhisa TANAKA and Rikuo OTA
Abstract:Ag2O-B2O3-Al2O3 glasses were prepared by melting and quenching method and the state of silver in the glasses was examined by optical absorption spectra. These glasses have two absorption peaks at less than 300nm and 320nm, which correspond to Ag+ ion and atomic Ag, respectively. The content of atomic silver increased with the increase of temperature. Metallic Ag (Ag colloid) precipitated at the glass surface by the heat-treatment at 400oC which causes the absorption peak at 440nm. The origin of the precipitated colloid was considered to be atomic Ag dissolved in the glass because the intensity of the absorption peak at 320nm decreased by the heat treatment. However, the precipitation mechanism is not clear. Since the peak of atomic silver was not observed for the slowly cooled glass, it is considered that the free volume at the glass surface which have high fictive temperature plays an important role for the precipitation of silver. Key Words:Optical absorption spectra, Precipitation, Silver colloid, Heat-treatment