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Bose peak and vibrational bands in Raman spectra of sodium borosilicate glass

The existence of an asymmetric broad band called boson (Bose) peak in VV as well as in VH polarized Raman spectra of sodium borosilicate glass with various amounts of SnO is shown and its bandshape fitted according to the formula I_VH ~ C(w) g(w) (n(w)+1)/w, where n(w) stands for Bose-Einstein occupation mnumber and C(w)g(w) is given by C(w) g(w) = w^5 / ( w^2 + (w_0)^2)^2. Parameter w_0 seems to depend on the chemical composition and the tzpe of glass. The low frequency band of our sodium borosilicate glass (1:1:4 molar ratio of Na_2O : B_2 O_3 : SiO_2) obeys this formula well, with w_0 = 52 cm-1, which is approximately the peak position of the band. On addition of SnO (1.5 to 10 wt %) the shape of boson peak in VH spectra changes on addition of 1.5 wt%, but remains unchanged on further addidtion of SnO. In the VV - 4/3 VH spectrum, a new peak around 530 cm-1 appears, indicating that tin ions behave as network formers.

sodium borosilicate glass ; disorder ; Raman ; Bose peak ; low frequency

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