Synthesis and characterisation of monodisperse zirconia particles

Monodisperse spherical ZrO2 particles were prepared by controlled hydrolysis of zirconium tetraalkoxide in alcoholic solution. Ageing the reaction solution at 60 degrees C for 4 h yields particles with sizes in the range between 200 and 2000 nm. The influence of various ions and surfactants on the final product was investigated. Stable suspensions of coated, monodisperse, zirconia particles were prepared by hydrolysis and subsequent polymerisation of tetraethoxysilane in an alkaline ethanol solution. Thermal analysis revealed that the weight loss of bound water occurred below 400 degrees C and is about 35 %. The phase transition from amorphous zirconia to the tetragonal phase proceeded at approximately 450 degrees C, the transition to the monoclinic phase began at about 600 degrees C and was completed at about 800 degrees C. The crystallinity of the powders was investigated by X-ray diffraction. Electrophoretic measurements were carried out to determine the charges on the particle surface. Elementary analyses were used for further investigations. On the basis of the results obtained, the mechanism of particle formation was discussed. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.