Composition Dependent Analysis Of Raman Spectra In The Modified Boroaluminosilicate System: Implications For Coupling Between Structural Resonance And Relaxation In The Glass Network

The boroaluminosilicate system was systematically modified by addition of magnesium, sodium and zirconium oxides. Strong bridging silicate bands as well as narrow and intense nonbridging silicate bands compose the Raman spectra of glasses. The fundamental nonbridging molecular species bands are related to the bridged network bands by the first overtone and signify anharmonic oscillation. As a constant degree of depolymerisation, the nonbridging band intensity depends on the silica content. With a decrease in silica content, the bridged network band frequency shifts to a higher value and simultaneously the nonbridging bands intensify. The sharp rise in intensity for the nonbridging bands is attributed to resonant oscillations between the bridged lattice network and nonbridging molecular species.