Vibrational spectra of bismuth silicate glasses and hydrogen-induced reduction effects

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Abstract Raman (10–1200 cm −1 ) and infrared reflectance (100–2000 cm −1 ) spectra are reported for bismuth silicate glasses of the formula x Bi 2 O 3 · (10− x )SiO 2 with x = 9, 8, 7, 6, 5, 4. The basic vibrational characteristics and the possible glass structure are discussed. The results provide evidence that bismuth oxide behaves as the network former while silicon oxide is present as isolated SiO 4 tetrahedra. Hydrogen treatment was performed at 300°C on a bismuth silicate glass with x = 5. The intensity of most Raman bands decreased with increasing exposure time. The infrared spectrum after reduction showed vibrational bands at 1124 and 1220 cm −1 which are characteristic of SiOSi stretching vibrational modes in a fused-silica network. The spectral changes observed indicate the formation of bismuth metallic colloids as well as the formation of the bridged SiOSi structure in the glass surface layer during reduction.