Résumé
Control of the surface areas of the calcined zirconium(iv) oxides arises from the extent of equilibration permitted between the hydrolysed zirconyl oxychloride and the surfactant prior to calcination. The properties of the zirconia-surfactant materials, which are formed by a scaffolding and controlled drying mechanism, and the subsequent oxides obtained on calcination depend more on the times allowed for equilibration than on the ratios of zirconia:surfactant. During the equilibration over
ca.
24 hr between the hydrolysing zirconium oxychloride and CTAB, the small, unstable zirconium oxide particles mix intimately with the surfactant. These particles recrystallise (and loosely aggregate) on calcination to give tetragonal zirconias of intermediate surface areas