Evolution of the Phase Content of Zirconia Powders Prepared by Sol-Gel Acid Hydrolysis

The evolution of the phase content in zirconia powders that have been prepared by sol-gel acid hydrolysis has been investigated using the perturbed-angular-correlation (PAC) technique and X-ray diffractometry. As a consequence of performing annealing treatments at increasing temperatures between room temperature and 1,000 C, the amorphous starting material transforms to the tetragonal form and then to the monoclinic form. The metastable tetragonal phase exhibits two hyperfine components, one of which describes very defective zirconium surroundings. The evolution of PAC relative fractions is in agreement with the diffraction results. The durability of the samples in sodium hydroxide seems to increase as the relative amount of the most-defective zirconium surroundings of the tetragonal form increases.