Phase formation in mixed TiO2-ZrO2 oxides prepared by sol-gel method

Pure titania, zirconia, and mixed oxides (3—37 mol.% of ZrO2) are prepared using the sol-gelmethod and calcined at different temperatures. The calcined samples are characterized by Ramanspectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electronmicroscopy, and nitrogen adsorption porosimetry. Measurements reveal a thermal stabilityof the titania anatase phase that slightly increases in the presence of 3—13 mol.% of zirconia.Practically, the titania anatase-rutile phase transformation is hindered during the temperatureincrease above 700 C. The mixed oxide with 37 mol.% of ZrO2 treated at 550 C shows a newsingle amorphous phase with a surface area of the nanoparticles double with respect to theother crystalline samples and the formed srilankite structure (at 700 C). The anatase phase is not observed in the sample containing 37 mol.% of ZrO2. The treatment at 700 C causes the formation of the srilankite (Ti0.63Zr0.37Ox) phase.