A. Nagai et al., CRYSTALLINE PRODUCTS AND THEIR FORMATION MECHANISM IN THERMAL HYDROLYSIS OF ZROSO4 SOLUTION, Journal of Materials Science, 30(13), 1995, pp. 3333-3338
Solid products were prepared from mixtures of zirconyl carbonate and s
ulphuric acid solution under thermal hydrolysis at 240 degrees C. Thes
e crystalline products and their formation mechanism were investigated
by evaluating the amount of products, and by X-ray diffraction analys
is and TEM observation. The solid products precipitated were zirconium
oxide sulphates (ZOS, PZOS, ZrOSO4 . H2O) and m-ZrO2. The area and th
ickness of the fine plate-like crystals of ZOS increased with increasi
ng concentration of the solution and hydrothermal treatment time. For
thin starting solutions, the precipitation velocity and the amount of
PZOS increased. For thick starting solutions, those of ZOS increased.
For 0.5 mol/l(-1) ZrOSO4 solution (ZS0.5) from the thin solution, PZOS
crystallized early and m-ZrO2 crystallized by releasing sulphuric aci
d ions in PZOS with treatment time. For ZS2.5 from the thick solution,
ZrOSO4 . H2O was crystallized by increasing the proportion of sulphur
ic acid ions to zirconium ions in the solution, which was caused by ZO
S precipitation.