Er-doped silica-titania multilayer coatings have been successfully deposited using an original sol-gel deposition technique: the Aerosol-gel process. This study is the first step toward Aerosol-gel preparation of active planar wave guides. In this paper, we report on the physical, chemical, optical, microstructural and spectroscopic properties of the multilayer coatings. A new optically active crystalline phase, Er2Ti2O7 (ETO), has been identified. This study shows that, depending on the experimental conditions (titanium and erbium content, heat treatment temperature), ETO can be obtained in the form of nanocrystallites dispersed in a transparent amorphous matrix.