Preparation and electrorheological property of Y4O(OH)₉(NO₃)-NH₄NO₃ materials

The new electrorheological (ER) material, a particle material composed of Y₄O(OH)₉(NO₃) and NH₄NO₃, was obtained. They display better ER performance. The shear stress of the suspension of Y₄O(OH)₉(NO₃) (NH₄NO₃)_2.8 material in dimethyl silicone oil reaches 1469 Pa at an electric field strength (E) of 4.2 kV·mm^-1 and the shear rate (γ) of 150 s^-1. The relative shear stress, τ_E/τ₀ (τ_E and τ₀ are the shear stresses at E = 4.2 and 0 kV·mm^-1, respectively), is up to 29, which is 19 times that of pure Y₂O₃ material. The dielectric and conductive property of the materials play important roles in the modification of the ER effect of the particle materials. The researches on these new ER materials are very useful for obtaining a better understanding on the mechanism of the ER effect and finding an ideal ER material.