Kinetic study on the effect of iron on the grain growth of rutile-type TiO₂ under in situ conditions

Abstract There have been many studies on the growth kinetics of titanium dioxide and doped titanium dioxide. However, most calculated the grain size after isothermal treatment and cooling to room temperature; thus, the real grain size of titanium dioxide at the real-time temperature during heat treatment could not be obtained. This study thus aimed to obtain accurate grain information during the heat treatment process. In this study, titanium oxysulfate (TiOSO₄) and ferric chloride (FeCl₃·6H₂O) were used to hydrolyze and precipitate TiO₂ precursors containing impurity iron. Then, the sample was subjected to high-temperature in situ x-ray diffraction. Using the Williamson–Hall mapping method to process the x-ray diffraction information, the grain size could be used to characterize changes in the grain size, and the change law of TiO₂ during the heat treatment process was studied. Furthermore, the effect of Fe doping on the growth of TiO₂ crystals was examined through the crystal growth kinetics. The results revealed that when the Fe doping amount reached a certain level, it affected the growth mechanism of the rutile type titanium dioxide grains, thereby causing a change in the growth order. Specifically, an increase in the Fe doping amount increased the growth activation energy; that is, it inhibited the growth of rutile-type titanium dioxide grains.