Mechanisms of an incipient reaction between Ca(OH)2 and SiO2 under mechanical stressing are studied mainly by detailed infrared (IR), X-ray photoelectron (XPS), and solid state 1HNMR spectroscopies. Pretreatments by H-D exchange, adsorption of pyridine or ammonia were carried out prior to IR spectroscopy. From the comparison between the separate and mixed-milling, a solid state acid-base reaction and simultaneous dehydration are revealed. Subsequent charge transfer, confirmed by XPS, leads to the formation of a precursor of complex oxides involving Ca-O-Si bonding.
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