水和ジルコニア微粒子の生成速度に及ぼすZrOCl₂濃度の影響

抄録

In present study, the relationships between the formation ratio and boiling time of hydrous-zirconia fine particles produced by the hydrolysis of aqueous solutions of ZrOCl₂ with 0.05-0.4mol⋅dm^-3 concentrations were investigated. In particular, emphasis was placed on examining the effect of the ZrOCl₂ concentration on the formation rate of hydrous zirconia. The formation time of hydrous-zirconia particles increased with increasing ZrOCl₂ concentration. X-ray diffraction measurements revealed that hydrous-zirconia particles synthesized at any ZrOCl₂ concentration were similar to those observed for monoclinic crystalline ZrO₂. Based on these experimental results, the formation-rate constants (κ) of hydrous-zirconia particles produced at 0.05-0.4mol⋅dm^-3 concentrations were determined experimentally by assuming the formation processes and estimating appropriate values for the acid-dissociation constants. It was clarified that the determined κ-value decreased with increasing ZrOCl₂ concentration. The decrease of the κ-value can be explained by the decrease of the κ(I)-term in the ionic strength function contained in κ.