Article ID Journal Published Year Pages File Type
1486125 Journal of Non-Crystalline Solids 2006 8 Pages PDF
Abstract
The time evolution of the tetraethoxysilane (TEOS)-based sol-gel process was investigated by EPR spectroscopy of a Mn2+ spin probe. Analysis of the EPR spectra recorded at room temperature (RT) and liquid nitrogen temperature (77 K) showed that the values of the g-factor (for the central Mn2+ sextet) were found to be, within experimental error, identical during the sol-gel process evolution. However, the peak-to-peak half width, ΔBpp, of the spectral lines recorded at RT, the splitting of the forbidden hyperfine lines (and thus the zero-field splitting parameter, D) recorded at 77 K, and the averaged hyperfine splitting constant, Aav, at both temperatures, were found to change significantly during the various stages of the sol-gel process. These EPR spectral parameters allow us to monitor changes in the TEOS-based sol-gel reaction mixture during the liquid-to-solid-state transition. It was clearly demonstrated that the sol-to-gel transition as well as the hydration and dehydration process of gels could be successfully studied by Mn2+ EPR spectroscopy.
Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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