Investigation of High-Pressure and Temperature Behavior of Surfactant-Containing Periodic Mesostructured Silicas

Surfactant-containing periodic mesostructured silica materials, namely SBA-16 and FDU-12, were studied under pressures between 1 and 4 GPa and temperatures between 100 and 400 °C. At 4 GPa crystallization of coesite can be achieved already at 200 °C. The mild transition of amorphous to crystalline silica is believed to be accomplished by the inbuilt hydroxyl groups present in the starting material. At 2 GPa the crystallization of quartz is accomplished at a temperature of 400 °C. Both quartz and coesite are obtained in nanocrystalline form