Abstract
The formation rate of hydrous-zirconia fine particles produced by the hydrolysis of various ZrOCl2 solutions (with and without an addition of NaCl, CaCl2 or AlCl3) were measured to investigate the effects of added metal chlorides on the formation rate. Chemical analysis and X-ray diffraction measurements revealed that the hydrous-zirconia particles synthesized in the present experiments contained little Na, Ca and Al, and were similar to those observed in monoclinic crystalline zirconia. Chemical kinetics analyses revealed that the formation-rate constants (k) of hydrous-zirconia particles, under constant ZrOCl2 concentration, decreased with increasing NaCl, CaCl2 and AlCl3 concentrations. The decrease in the formation rate upon addition of the above metal chlorides can be explained by the decrease of the k(I)-term in the ionic strength function contained in k, and the blocking action of the hydrolysis attributed to the ligand-substitution reaction between H2O molecules coordinated to Zr atoms and Cl- ions.
