The inset of each figure in Fig. 4 shows the change of Raman scattering intensity with respect to Al2O3 content. It is seen that there exist drastic intensity changes even with a small amount of
Al2O3 variation. With the increase of Al2O3 contents, the peak intensity at 485 cm1 increases but the intensities at 560, 615 and 650 cm1 in Fig. 4(a) decrease and almost disappear after
6mol%ofAl2O3. As explained previously, Raman scattering in the range of 485 cm1 is related to the vibration of low dimensional network binding such as B–O–Si, B–O–Band Si–O–Si. Meanwhile other peaks are concerned with the vibrations of high dimensional network binding of BO4 tetrahedral units. These indicate that Al2O3 acts as a network modifier and disconnect network connection, and these effects appear as an increasing population of the low dimensional
bindings and a decreasing population of the high dimensional structural units. A similar explanation can be adopted to explain the change of Raman peak intensities in Fig. 4(b) and (c).