Abstract
The alumina gels which form α-Al2O3 at heat treatment temperature as low as -500°C were prepared from aluminum-sec-butoxide by the sol-gel method under the ambient condition. Preparation of transparent alumina sol by hydrolysis of the alkoxide at a low temperature such as 0°C and aging the sol at a moderately low temperature, typically 8°C for a relatively long time up to 30 days were found to be important for obtaining such alumina gels.
