New Sol–Gel Route for the Preparation of Pure α‐Alumina at 950°C

Abstract

An anhydrous alumina (Al 2 O 3 ) sol was prepared from aluminum isopropoxide and an organic solvent, using an acetic acid stabilizer. The complete conversion of the dried sol to α‐Al 2 O 3 was accomplished at a temperature of 950°C by a single transition via γ‐Al 2 O 3 . Al 2 O 3 that was deposited via dip coating resulted in amorphous films, even after annealing at 1100°C, because of the silicon diffusion from the substrate. This phenomenon was avoided using a rapid thermal treatment in a flame after dip coating, which resulted in uniform thin films that are converted to α‐Al 2 O 3 via heat treatment.