Electrorheological effects of cerium-doped TiO₂

It is found that the doping of cerium ion into anatase TiO₂ can improve the electrorheological (ER) effects of TiO₂ and broaden the operational temperature range. Especially, the substitution of 7-11 mol% of the cerium dopant for Ti can obtain a relatively high shear stress, τ = 7.4 kPa (at 4 kV/mm), which is ten times larger than that of pure TiO₂ ER fluid. Also, the typical Ce-doped TiO₂ ER fluid shows the highest shear stress at 80°C, but 40°C for pure TiO₂ ER fluid. The dielectric loss and dielectric constant at a low frequency of TiO₂ is improved by the doping of cerium, and the temperature dependence of the dielectric properties shows an obvious difference between pure and doped TiO₂ ER fluids. These can well explain the ER behaviour of doped TiO₂. Furthermore, the change of rheological and dielectric properties is discussed on the basis of the lattice distortion and defects in TiO₂ arising from the doping of cerium.