Aluminium sulfate solution was prepared by sulfuric acid treatment from gibbsite. Aluminium sulfate hydrate [
_3$})
·

] was precipitated from aluminium sulfate solution by adding it into ethylalcohol. From XRD analysis as-prepared
_3$})
·

was confirmed to have mixed-crystalization water(n=18, 16, 12, 6). The average water of crystalization calculated from thermogravimetry(TG) was 14.7. Aluminium sulfate hydrate [
_3$})
·

] was thermally decomposed and converted to
_3$})
at

,

at

, and

at

. Ni-doped

, was synthesized from the slurry of as-prepared

, with the ratio of [Ni]/[Al]=0.5. The reaction conditions of synthesis were determined as initial pH 9.0 and temperature

The basicity(pH) of slurry was controlled by using urea and

solution. Urea was also used for deposition-precipitation. For determining termination of reaction, the data acquisition was performed by oxidation reduction potential(ORP), conductivity and pH value in the process of reaction. Termination of the reaction was decided by observing the reaction steps and rapid decrease in conductivity. On the other hand, BET(Brunauer, Emmett and Teller) and thermal diffusity of Ni- doped

, with various content of Ni were measured and compared. Thermal stability of Ni- doped

at

was confirmed from BET and XRD analysis. The surface state of Ni-doped

was investigated by X-ray photoelectron spectroscopy(XPS). The binding energy at

increased with increasing the formation of

phase.