The structure of mechanically induced precursor in an amorphous state between Ca(OH)2and SiO2was determined by solid state MAS and CP/MAS29SiNMR spectroscopies, and the changes in the behavior of crystallization by linear heating were studied by X-ray diffractometry. A large broad Q0peak due to the short-range order of hydrated calcium silicates appeared in the29SiNMR spectra of mechanically induced precursors. The formation of the new ordering is confined in the near-surface region of SiO2particles, as confirmed by comparing MAS and CP/MASNMR spectra. When the amorphous precursor obtained above was subsequently heated, a rapid solid state reaction led to single phasedα-CaSiO3as the final product.
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