RAMAN-STUDY OF BI2O3-GEO2-SIO2 GLASSES

Raman spectra have been obtained for 2Bi(2)O(3)-3[(GeO2)(x)-(SiO2)(1-x )](2-3 composition) and 6Bi(2)O(3)-[(GeO2)(x)-(SiO2)(1-x)] (6-1 compos ition) glasses at different Ge/Si nominal ratios. In both compositions , the vibrational structure at low frequencies is nearly independent o f x. At higher frequencies, typical vibrations are found which may be attributed to Ge-O and Si-O bonds in GeO4 and SiO4 tetrahedral units, respectively, as observed in mixed crystals with the same stoichiometr ic formula.