Investigation of Al-O-Al sites in an Na-aluminosilicate glass

This paper reports the presence of Al- O- Al linkages in an aluminosilicate glass where Si/Al = 1 by using 2D¹⁷O triple quantum MAS NMR technique (3Q MASNMR). The experiments were performed at external magnetic fields of 8.4 and 14.4T. Despite¹⁷OMAS NMR spectra of the sample in both fields do not give much information about the different kinds of linkages in the sample, 3Q MAS NMR spectrum shows clear evidence that there are some amounts of Al-O-Al linkages in the sample giving two completely resolved peaks. These two peaks were attributed to the Si-O-Al and Al-O-Al linkages on the basis of their chemical shifts and, quadrupolar coupling constants which are quite sensitive to the local structure.