A novel preparation process for thermally stable ultrafine tetragonal zirconia aerogel Original Research Article

A novel sol-gel-supercritical fluid drying (sol-gel-SCFD) process is proposed to prepare ultrafine zirconia powder material. The X-ray diffraction (XRD), transmission electron microscopy (TEM), full nitrogen adsorption/desorption (77 K) and thermo-gravimetric (TG), differential thermo-analysis (DTA) were utilized to characterize the phases, morphology, particle size and microstructure of the derived zirconia aerogel. The results showed that the mean crystalline size (Dhkl) is about 4.3 nm and the sample consists of clusters of cross-linked particles. The calcination at a higher temperature (i.e. 1020 K) only causes slightly crystallite growth (up to 5.4 nm) and almost without the transition of the tetragonal to monoclinic phase. It is concluded that the ultrafine zirconia aerogel, which showed a high thermal stability, large surface area as well as pore volume, can be prepared by the novel sol-gel-SCFD method.