Preparation and electrorheological characteristic of Y-doped BaTiO3 suspension under dc electric field

The electrorheological (ER) effects of BaTiO3 or other perovskite materials with high dielectric constant are presumed to be large. However, their weak ER activity is very puzzling. In this study, we choose cubic BaTiO3 and first achieve its ER enhancement under dc electric field by modifying its intrinsic structure with doping rare earth Y ions, which are synthesized by means of sol-gel technique. DSC-TG, FT-IR, XRD, ICP and XPS techniques are used to characterize thermal, structure and component change of materials. It is demonstrated that Y3+ substitutes for Ba2+, which causes lattice-distorting defects. Rheological experiments show that Y-doped BaTiO3 suspension has notable ER effect and clear fibrillation structure under dc electric field, while the pure cubic BaTiO3 suspension suffers from electrophoretic effects and its ER effect is very weak. The ER effect of typical Y-doped BaTiO3 ER suspension is ten times that of pure BaTiO3 ER suspension. Based on the electrical measurements, the enhancement of ER activity of BaTiO3 may be attributed to the increase of conductivity due to Y-doping. The enhancement in ER activity of cubic BaTiO3 under dc electric field by doping rare earth Y ions is helpful to further understand the perovskite-based ER materials with high dielectric constant but low ER activity. (C) 2004 Elsevier Inc. All rights reserved.