B12-induced formation of stishovite in sol-gel produced amorphous SiO2 matrices Article uri icon

abstract

  • Composites containing vitamin B12 (cyanocobalamin) dispersed in amorphous silica xerogel were studied structurally as a function of annealing temperature. Silica xerogel samples were prepared by the sol-gel method using an ethanol:H2O:TEOS molar ratio of 4:11.6:1 and loaded with cyanocobalamin. We found that the structure of the cobalamin is unaltered, although decoordination of the benzimidazole nucleobase of B12, whereas the amorphous quartz structure of the matrix is maintained under heat-treatment without low-cristobalite phase transformation, typically of this kind of materials. We found in our samples partial crystallization of the glass matrix in form of stishovite obtained at very lower pressure than those specified by the phase diagram, and temperatures about 400 °C due to the presence of vitamin B12. The presence of stishovite is corroborated by the Rietveld refinement method. © 2011 Springer Science Business Media, LLC.
  • Composites containing vitamin B12 (cyanocobalamin) dispersed in amorphous silica xerogel were studied structurally as a function of annealing temperature. Silica xerogel samples were prepared by the sol-gel method using an ethanol:H2O:TEOS molar ratio of 4:11.6:1 and loaded with cyanocobalamin. We found that the structure of the cobalamin is unaltered, although decoordination of the benzimidazole nucleobase of B12, whereas the amorphous quartz structure of the matrix is maintained under heat-treatment without low-cristobalite phase transformation, typically of this kind of materials. We found in our samples partial crystallization of the glass matrix in form of stishovite obtained at very lower pressure than those specified by the phase diagram, and temperatures about 400 °C due to the presence of vitamin B12. The presence of stishovite is corroborated by the Rietveld refinement method. © 2011 Springer Science%2bBusiness Media, LLC.

publication date

  • 2011-01-01