Fig. 1: 29Si MAS NMR spectra of the
(CaO)x(Na2Si3O7) glass series.
Chemical shift values, line widths and relative abundances of different Qn species
were obtained by curve fitting assuming Gaussian line shapes for each component.
The top two spectra comprise Q4 and Q3 contributions only, while the
remaining spectra are best represented with three components (n=2,3,4). The position of the
Q4 line is stable at -106.9ppm. Q3 become deshielded (-94.1ppm to -91.7ppm)
while Q2 become shielded (-81.5ppm to -83.9ppm) with increasing CaO content.
The line width of the Q4 decreases, that of the other components increases as more
CaO is added.