Electrorheological fluids containing Ce-doped titania

A new type of water-free electrorheological (ER) material of anatase titania doped with Ce has been synthesized by a sol-gel technique. The thermal character and crystal structure of doped titania are characterized with FT-IR, DSC-TG and XRD. The ER behaviors of the suspension made of such particles dispersed in silicone oil at a volume fraction of 18% are investigated in a DC electric field. The results show that the doped titania ER suspension has a much increased shear stress compared with the pure titania one. The shear stresses of 1.7 kPa at 3 kV/mm and 2.6 kPa at 4 kV/mm can be induced in a 8.5 mol% cerium-doped titania ER suspension, which is 5 times higher than that of the pure titania one. Moreover, the induced shear stress has a significant dependence on the Ce/Ti molar ratio and the maximum shear stress can be obtained when Ce/Ti molar ratio is about 0.1. In addition, significant differences in the temperature dependence of shear stress between the pure and doped titania ER suspensions are found. The working temperature range is extended by Ce doping. The obvious improvement in the ER effect resulting from Ce doping can be explained in terms of the dielectric and conduction properties of the ER suspensions.