High Pressure Synthesis versus Calcination – Different Approaches to Crystallization of Zirconium Dioxide

Calcination and microwave-assisted hydrothermal processing of precipitated zirconium dioxide are compared. Characterization of synthesized products of these two technologies is presented. The infiuence of thermal treatment up to 1200^oC on the structural and spectroscopic properties of the so-obtained zirconium dioxide is examined. It was found that initial crystallization of material inhibits the crystal growth up to the 800^oC (by means of XRD and TEM techniques), while the material crystallized from amorphous hydroxide precursor at 400^oC, exhibits 26 nm sized crystallites already. It was found using the TG technique that the temperature range 100–200^oC during the calcination process is equivalent to a microwave hydrothermal process by means of water content. Mass loss is estimated to be about 18%. Based on X-ray investigations it was found that the initial hydroxide precursor is amorphous, however, its luminescence activity suggests the close range ordering in a material.