PHASE TRANSFORMATION OF TiO_2 ULTRAFINE POWDERS FROM AQUEOUS TiOCI_2 SOLUTION DURING HOMOGENEOUS PRECIPITATION

摘要

Crystalline TiO_2 ultrafine powders have been prepared by the homogeneous precipitation method simply by heating an aqueous TiOCI_2 solution below 70℃. With the spontaneous hydrolysis of the aqueous solutions, all the precipitates were fully crystallized in the rutile TiO_2 phase, which was transformed to the anatase TiO_2 phase as increasing the addition of TiOSO_4 solution to the aqueous TiOCI_2 solution. These precipitates were formed with spherical secondary particles which consisted of acicular, spherical and mixed primary particles corresponding to the rutile, anatase and mixed phases, respectively.