Dependence of moisture absorption property on sol-gel process of transparent nano-structured γ-Al2O3 ceramics

Nano-structured γ-Al2O3 ceramics have been prepared from Al-Sec-Butoxide (C12H27AlO3) by sol-gel process to investigate and evaluate the characteristics as a humidity sensor. It is found that they have a good response for extremely low ppmv moisture. γ-Al2O3 ceramics contains pore size less than 4 nm and shows sensitivity down to 3.0 ppmv. Sol-gel process has been used to fabricate monolith substrate thickness 65 μm for making moisture sensor. The most important advantages of sol-gel processing over conventional coating methods are the easier fabrication of films or coatings of complex oxides and easier control of composition and microstructure of the deposited coating compared to conventional thin film technology.