Comparative Raman Study of Mixed-Alkali and Similar Ion Exchanged Glasses.

The Raman spectra of analogous ion exchanged and mixed alkali disilicate and aluminodisilicate glasses of the same relative composition of dissimilar cations have been determined and employed to investigate the origin of the similarity of the mechanical loss features exhibited by them. Ion exchange of Na for Li in Li2O-Al2O3-2SiO2 glasses is shown to yield glasses whose network structure is different from that of the mixed alkali glasses of the same stoichiometry, but to attain that structure upon annealing. The network structure of ion exchanged and conventionally mixed alkali disilicate glasses are apparently identical. These results are interpreted in light of the mechanical loss spectra of the analogous glasses prepared in the two ways. Author