Study On Crystal TiO₂ Films Coating On Fe₃O₄ Particles

It is investigated that TiO₂ flims were prepared to cover the surface of nano- and micro- scaled Fe₃O₄ particles. XRD was used to characterize the crystal phase, resistance to high concentration HCl was adopted to analyse the surface coverage, and magnetized intensity was measured through the hysteresis loop.It is indicated that the sol-gel method can not make the TiO₂ coated thoroughly around the magnetic particle surface, the liquid phase deposition was efficient to prepare TiO₂ covered magnetic particle surface. Calcination is benefit to increase the TiO₂ coverage on the surface.Effects of Fe/Ti molar ratio, surface modification and feeding orders on the TiO₂ coating were studied using the liquid phase deposition. The optimal conditions were obtained: Fe/Ti molar ratio was 1:0.77, the solution was added for 4 times, for nano-sacled Fe₃O₄, the coverage ratio was 25.6%, and the magnetized intensity was 22.86emu/g; for micro-scaled Fe₃O₄, the coverage ratio was 5.2%, and the magnetized intensity was 50.41emu/g.It is indicated that using ionic surfactants to modify the magnetic particle surface was not efficient to the TiO₂ coverage on the surface. Changing the feeding order, namely adding the solution for 4 times can decrease the coverage ratio, but it can increase the magnetized intensity.