Atomic scale structure of alcohol-based zirconia xerogels by X-ray diffraction

The structural evolution of zirconia thin films and gel powders obtained from an alkoxide precursor has been evaluated by X-ray diffraction (XRD). The results indicate that the topological short-range structure (<5 Å) of amorphous alcohol-based zirconia materials is independent of the product form (gel powders or thin films). However, the short-range structure depends on the processing temperature. For temperatures below ∼340°C, local atomic ordering of both ZrO2 gel powders and films resembles that of crystalline monoclinic ZrO2. An alcoxolation mechanism appears to control thin films polymerization processes, while an oxolation mechanism appears responsible for ZrO2 gel powders polymerization. At higher temperatures, the local atomic structure of both amorphous ZrO2 gel powders and films resembles that of crystalline tetragonal ZrO2 polymorph. Tetragonal ZrO2 crystallites were also observed by XRD analysis in all ZNP-based zirconia samples processed above 340°C.