Preparation of SiO₂-TiO₂ graded glass by using high gravity field combined with sol-gel method

A method to prepare the multi-component oxide glass with graded structure was proposed. This method is based on the facts that colloid particles can sediment during a sol-gel transition process under comparatively low gravity field, and the resultant gel can be converted into glass at lower temperature treatment than a conventional method. The graded structure was formed by centrifuging (10,000 g level) the Si and Ti mixed colloids, and immobilized by removal of solvent at 90 °C. This graded precursor gel was heated to 900 °C to convert into a glass state. The proper condition to prepare the graded glass was examined especially focusing on the growth time of colloids before the centrifugation. A transparent SiO₂-TiO₂ glass with molecular-scale graded structure was obtained in many trials.