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

• An environmentally friend process to prepare Fe 2 O 3 /TiO 2 by wetness impregnation method. • Excellent electrorheological response of fluids with 4 vol% of particles. • The measurements can be performed until 4 kV/mm without breakdown. • Excellent reversibility, stability and rapid response of ERF under electric field. • Slight increase in shear stress at low shear rate with temperature under EF. Iron-doped titania (Fe 2 O 3 -TiO 2 ), 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 Fe 2 O 3 /TiO 2 –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 % Fe 2 O 3 /TiO 2 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.