金属アルコキシドから作ったAl₂O₃-SiO₂系ゲルの構造に及ぼす加水分解条件の影響

抄録

The effect of hydrolysis conditions on the structure of gels was studied on the Al-O-Si alkoxides containing up to 33mol% Al₂O₃ in the system Al₂O₃-SiO₂. The synthesized Al-O-Si alkoxides consisted of chainlike polymers, which were aggregated into three-dimensional branched polymers with increasing water content. Alkoxide solutions which were hydrolyzed with more than 4 moles of water and HCl of low concentration comprised three-dimensional branched polymers, in which Al³⁺ ions were mainly four oxygen-coordinated. And the gels were considered to consist of the aggregates of primary particles with a diameter of 70Å. On the other hand, when hydrolyzed with more than 4 moles of water and HCl of high concentration, Al³⁺ ions became six oxygen-coordinated, which resuted in disaggregation of three-dimensional branched polymers into chain-like ones. In gels from this solution, water remained even on heating at high temperature.