The Influence of pH on Zirconia Formed from Zirconium(IV) Acetate Solution: Characterization by X-Ray Powder Diffraction and Raman Spectroscopy

The influence of the pH of the reaction mixture on the nature of zirconia formed from zirconium(IV) acetate solutions, processed either by boiling under reflux or by hydrothermal methods, has been investigated. The resulting gels and powders were calcined in air at various temperatures and characterized using X-ray powder diffraction and Raman spectroscopy. The latter technique was found to be superior in differentiating between tetragonal and cubic zirconia. Zirconia formed from solutions of high pH was found to contain a greater quantity of the tetragonal polymorph, suggesting that the addition of alkali to the solution tends to stabilize the tetragonal form against conversion to the monoclinic form. The high pressure associated with the hydrothermal treatment is important for the direct formation of monoclinic zirconia under acidic conditions.