A new class of electrorheological material, preparation and electrorheological property of K₂O-doped Y₂O₃ material

A new class of electrorheological (ER) material using rare earth yttrium oxide as the substrate, K₂O-doped Y₂O₃ materials, have been synthesized using K₂CO₃ and Y(NO₃)₃ as starting materials. Their ER performance, dielectric property and microstructure have been studied. The results show that the K₂O doping can markedly enhance the ER activity of the Y₂O₃ material. A clear dependence of the ER effect on the degree of K₂O doping has been observed. The shear stress of the suspension (25 wt%) of a K₂O-Y₂O₃ material (K/Y = 0.4, molar ratio) in dimethyl silicone oil reaches 1.6 kPa at electric field strength E = 4.2 kV/mm and shear stress rate γ = 300 s^-1, and its relative shear stress τ_r, which is defined as the ratio of shear stress at E = 4.2 kV/mm to zero-field shear stress (τ_r = τ_E/τ₀), reaches 6.6, which is six times higher than that of pure Y₂O₃. Investigations on relationships between ER effect and the microstructure and dielectric property of the materials indicate that the microstructure plays an important role, and dielectric property is a dominant factor in the modification of the ER effect of the particle materials. The results obtained in the research for these new ER materials is helpful for understanding further the mechanism of the ER effect and improving the ER material.