From a microwave flash-synthesized TiO2 colloidal suspension to TiO2 thin films.

Titanium(IV) oxide thin films have been prepared by dip-coating at ambient temperature from a TiO2 colloidal suspension. Prior to deposition, this suspension was synthesized by microwave-induced thermal hydrolysis of a titanium tetrachloride aqueous solution in the presence of hydrochloric acid. The effects, on film roughness and film thickness, of substrate, number of layers, substrate withdrawal speed, and heat treatment temperature were investigated on different observation scales. The microwave-born oxide nanoparticles showed good affinity to glass and silicon substrates; 10- to 50-nm-thick thin films, with absorption edge blue-shifted compared to bulk anatase, were obtained through a simple process without the need of heating treatment for crystallization purposes.