Correlations between data of 29Si NMR and thermogravimetry for silica/monetite nanocomposites

Silica/monetite nanocomposites were synthesized through controlled hydrolysis of tetraethoxysilane at concentrations of 5, 10, 15, and 20% mol/mol of calcium phosphate forming the solids named CaPSil1, CaPSil2, CaPSil3, and CaPSil4, respectively. XRD patterns showed formation of nanocomposites with a decrease in crystallinity. The NMR ²⁹Si spectra suggested an increase in the content of incorporated silica with reduction of Q³ (–SiOH) signal, which contributes for mass loss, in agreement with thermogravimetry. The incorporation of silica increased the chemical stability of the precursor phosphate in an acidic medium.