Thermal behavior of Ti-precursor sols for porous TiO2 thin films

Commercially available sols of amorphous TiO2 and anatase particle of nano-size has been precipitated and dried carefully. The solids obtained have been studied by simultaneous thermogravimetric and differential thermal analysis (TG/DTA) coupled with on-line evolved gas analysis (EGA) methods in flowing air and helium atmosphere in order to check and model pyrolytic processes taking place at elevated temperature ranges of anatase film formations by spray pyrolysis deposition (SPD). eating finely powdered amorphous TiO2, a mass loss and related carbon dioxide formation have been detected already at around 260 °C by a quadrupole mass spectrometer coupled to the thermobalance (TG/DTA–MS). The evolution of this strongly bound CO2 has been accompanied, even in pure helium, with an exothermic heat effect, which could be assigned to a simultaneous stabilization of the amorphous particles with high porosity by crystallization into anatase. Both increased crystallinity and improved solar efficacy has been achieved by a partial mixing with anatase sols as seeding crystals in the SPD process.