The effect of iron ions on the anatase-rutile phase transformation of titania (TiO2) in mica-titania pigments

摘要

Rutile TiO2-coated mica-titania pigments were prepared by hydrolysis of titanium tetrachloride in the presence of Fe~(3+). After calcination at 700 °C for 2 h, T1O2 nanolayers in rutile phase were formed on the mica surfaces. The morphology and the anatase-rutile transformation were probed by scanning electronic microscopy (SEM) and X-ray diffraction (XRD) respectively. SEM micrographs show that the dopants enhance the growth of particles of TiO2 thin layers. The change of lattice parameters confirms that Fe~(3+) enter ariatase structure and affect the anatase-rutile transformation. For the iron loading regime studied here, the anatase-rutile transformation is inhibited at low dopant levels with respect to undoped titania. While the anatase-rutile transformation is promoted as iron loading is increased. Moreover, synthesized pH value also has a pronounced effect on the anatase-rutile transformation and a highly acidic environment favors the formation of rutile.