The structural changes of silica gel by compressions up to 5GPa at 100 ºC

Abstract

TEOS-derived synthetic silica gels were compressed by Multi anvil apparatus under 2 and 5GPa at 100 °C. The recovered sample from 2GPa shows the crystallization to low-quartz. However, some parts of the sample remain the feature of as-prepared silica gel. Water molecules and silanol may promote this crystallization, i.e., the part which includes the high water content could crystallize to low-quartz. The recovered sample from 5 GPa was crystallized to coesite. However, water molecules and silanol groups are remained even after coesite crystallization.