Partial crystallization in exotic phase stishovite of amorphous silica xerogels induced by incorporation of chlorophyll species

Using the Rietveld refinement, we analyze the structural evolution under thermal treatment of silica xerogel samples with incorporation of extract from frozen spinach leaves, prepared by sol?Cgel method with low molar ratio (R) of water to TEOS of R?=?1, and R?=?5. Partial crystallization of silica xerogel in the form of stishovite has been obtained at atmospheric pressure conditions and temperatures of 200?°C, they both, very lower than those specified by the phase diagram, in samples containing chlorophyll aggregates dispersed in amorphous silica. The results show that the incorporation of spinach extracts leave together with low water contents induce devitrification of the silica matrix in exotic phase stishovite.