The structure of borosilicate glasses studied by Raman scattering

Raman spectra of alkali and alkaline earth borosilicate glasses are reported. These spectra are used to discuss the molecular structure of the glasses. The influence of Al₂O₃ additions on the structure of borosilicate glass is also discussed. It is shown that the same type of groups are present in borosilicate glasses as in borate and silicate glasses. The presence of large borate groups such as tetraborate and metaborate groups is strongly suggested by the Raman spectra. It appears that boron ions are hardly taken up in the silicon-oxygen network. Our results suggest that the region of phase separation is larger than the region presently acknowledged.