Electron microdiffraction studies of zirconia particles

A batch of zirconia was prepared at a pH of 2.95 using a sol-gel technique. The crystal structures formed during 500 °C calcination was followed by X-ray diffraction. The tetragonal phase was the major component after the initial calcination period of 15.5 h; however, it gradually transformed to the monoclinic crystal form during 200 h of calcination at 500 °C. Electron microdiffraction was employed in the present investigation to determine the crystal structure of individual particles, and to identify whether these particles contained twin variants. A technique has been developed to get a dispersion of agglomerated particles by condensing and spreading the beam on the agglomerates at 200 kV. The data revealed that some of the individual zirconia particles are featureless and some of them appear to contain single or multiple twin variants.