Atomic-Scale Structure of Water-Based Zirconia Xerogels by X-Ray Diffraction

The structural evolution of zirconia thin films and gel powders has been evaluated by X-ray diffraction. Maxima (r1 and r2) of the experimental radial distribution function RDF and the bond angles θ were determined and correlated with TGA (thermogravimetric analysis), DTA (differential thermal analysis) and MS (mass spectrometry). The results indicate that the topological short-range structure (<5 Å) of amorphous zirconia thin films, independent of drying temperature, resembles that of crystalline tetragonal ZrO2. In contrast, amorphous zirconia powder gels dried at temperatures below 120°C show atomic arrangements similar to that of tetragonal ZrO2. The structure of these gels annealed at temperatures between 165–340°C resembles a distorted tetragonal ZrO2, monoclinic-like structure. Zirconia powders and films contain crystalline tetragonal ZrO2 at 400°C.