Electrorheological behavior of titania nanoparticles modified with iron (III) oxide

Abstract

Iron-doped titania (Fe₂O₃-TiO₂), with 0.5, 1.0 and 1.5 wt% of iron, was prepared using the environmentally friendly and cost-effective incipient wetness impregnation method and dispersed into silicone oil (4.0 vol%) to evaluate the electrorheological (ER) performance, using controlled shear stress (CSR) and oscillatory mode. An excellent ER response was observed for all Fe₂O₃/TiO₂–based fluids, reaching yield stress values of around 274 Pa under an electric field strength of 4 kV/mm. Furthermore, the fluids displayed excellent reversibility and stability under the action of the electric field. The effect of the temperature on the electrorheological properties was also evaluated using an electrical field strength of 3 kV/mm. At low shear rate, the yield stress increased with the temperature, indicating an increase of the polarization of the particles. Although all particles displayed similar density, the better stability towards sedimentation was observed for the fluid containing 1.5 % Fe₂O₃/TiO₂ particle. Finally, from dielectric analysis, it was demonstrated that the dispersions provided relaxation time in the order of 10⁻⁴ s, which explains the rapid ER response with on–off experiments. Considering the simple particle synthesis and the good ER response including reversibility, these nanoparticles constitute promising candidates for practical applications.