The influence of long additional thermal treatment of controlled porous glasses on the structuralization of their silica network

The materials used as sorbents in gas and liquid chromatography include controlled porosity glasses (CPG). The heating of CPG in the temperature range 400–800 °C leads not only to dehydroxylation of their surface, but also to a diffusion of the boron atoms (and a smaller amount of sodium atoms) remaining in the silica network of the CPG towards the glass surface. Simultaneously, crystallization of the silica network of the CPG takes place. The present paper deals with the changes of the crystallographic structures in thermally treated glasses which differ in their mean pore diameters. The results show not only the existence of cristobalite in the siliceous lattice of the heated glasses, but also the presence of α-quartz, the very symmetrical structure of SiO2.