Porosity and texture of basic zirconium nitrate

Studies have been made of the development of texture and porosity in basic zirconium nitrate samples subjected to heat treatment at temperatures between 25 and 500°C. Scanning electron microscopy indicates that progressive disintegration of the amorphous material occurs over this temperature range, generating approximately spherical particles. Nitrogen gas adsorption studies, supplemented by mercury porosimetry measurements, show that these particles possess some microporosity (pore diameter < 2 nm), although the major factor controlling their adsorptive properties is an intrinsic mesoporosity related to a pore diameter within the range 2–50 nm and produced by the successive elimination of water and nitrato ligands with increasing temperature. Crystallisation occurs when the system is heated above 500°C, leading to the conversion of the amorphous material to the cubic variety of zirconia.