Effect of Synthesis Parameters on Zirconia Phases: Tetragonal or Monoclinic?

Abstract

Samples of ZrO2 were prepared by different procedures in order to figure out the most active tetragonal phase. Preparation methods differed in factors such as pH, precipitation temperature, calcination temperature, and the kind of zirconium salt (ZrOCl2 or ZrCl4). The products were characterized by XRD. It was found that the two types of salts show adverse results under the same preparation conditions. Contrary to the sample prepared using zirconium oxychloride, which showed a better result in pH between 9 and 10, the zirconium chloride samples showed a weak tetragonal peak in pH 9. In addition, Diffuse Reflectance Spectroscopy (DRS) was carried out to investigate the optical absorption properties. DRS analysis showed a strong absorption peak at about 220–230 nm and the estimated optical band gap was around 5 eV in most samples. The surface morphology of ZrO2 samples was analyzed by FESEM. The size of crystals did not change significantly with variations in calcination temperature.