Abstract
Three different magnesium silicate sols were prepared from Mg(OMe)2 and TEOS for which hydrolysis with H2O2 and H2O was under stoichiometric, stoichiometric, or over stoichiometric. Xerogels were prepared from the sols by simple evaporation, spray-drying, or freeze-drying. The freeze-dried precursor formed mostly protoenstatite, a high-temperature polymorph of enstatite (MgSiO3) that is generally not stable at room temperature; the other precursors formed mixtures of protoenstatite and clinoenstatite. The three xerogels and their calcined products were studied with XRD, HTXRD, BET, carbon analysis, TG/DTA and29 Si-NMR. Residual carbon was found to be an important factor in the crystallization, and 29Si-NMR spectroscopy was found to be a better tool than XRD to assess the phase purity of protoenstatite.
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Jones, S.A., Burlitch, J.M., Duchamp, J. et al. Sol-Gel Synthesis of Protoenstatite and a Study of the Factors That Affect Crystallization. Journal of Sol-Gel Science and Technology 15, 201–209 (1999). https://doi.org/10.1023/A:1008728724009
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DOI: https://doi.org/10.1023/A:1008728724009