*6% 102 0% 102
 400

 350

 300



 0)
 S150--
 W
 100-

 50


 0 200 400 600 800
 Curing Temp (OC)

Figure 4-13. Effect of curing temperature on surface area.

 The anatase phase of TiO2 begins transforming into rutile phase at a temperature

of 600C and becomes complete at 1000C (Zhang et al., 2001). It was thought that the

shift in the phase of titania at 800C may have also affected its photocatalytic ability, but

XRD analysis (Figure 4-14) revealed only a slight shift from the anatase phase (29 =

25.3) to the rutile phase (29 = 27.4) at 800C which may or may not be enough to have

caused a drastic decrease in destruction. It may also be that the phase change is mostly

occurring on the surface of the titania where the reactions take place. In other words, the

large anatase peak is due to internal anatase crystal formation and the rutile formation is

occurring foremost on the surface where it is greatly affecting photocatalysis.