Mechanochemical synthesis of ultrafine ZrO2 powder

The synthesis of ultrafine zirconia powders by mechanochemical reaction of ZrCl4 with CaO has been investigated using x-ray diffraction, TEM and DSC measurements. Mechanical milling resulted in a nanoscale mixture of CaO and amorphous ZrCl4, with no evidence of any reaction having occurred. Subsequent heat treatment at temperatures above 300 degrees C resulted in the formation of separated particles of cubic ZrO2, 5-10 nm in diameter, within an CaCl2 matrix. Measurements of the effect of particle size on the crystal structure of ZrO2 are also reported.