Grain Growth Kinetics of TiO2 Nanocrystals
Grain Growth During Heat-up and 2 H Soaking Time
The morphology of the nano-size titanate is shown in Fig. 4a. Images of layers in 300-700 °C are obtained in bulk of layers and not exactly clear because structure of layers between these temperatures have large amount of polymer.
Using the image analysis technique, the average grains size of TiO2 film calculated. After sintering at 300-800 °C with soaking time 2 h, average grains sizes were 25-190 nm, approximately.
The plots of fractal dimension and grain size during heat-up with 2 h soaking time is displayed in Fig. 4b and c.
The rapid grain growth during this stage of sintering is easily observed from Fig. 4a and b after sintering at 800 °C.
Figure 4c shows variation of fractal dimension of nano structure TiO2 at different temperatures with 2 h soaking time. According to this figure, surface of layer will be smooth after heat treatment at 600 °C, and hence leads to fractal dimension decreased. It can be seen, the size of fractal dimension is not depended on area selected (every box in Fig. 4c shows pixel of the selection area).