Anisotropic dielectric properties of structured electrorheological fluids

We present an approach to monitor the structure-induced anisotropic dielectric properties of electrorheological fluids. The particles used are made from uniform glass microspheres coated with an inner magnetic layer and an outer dielectric layer. Under an applied magnetic field, the particles are found to form columnar structures with a body-centered-tetragonal crystalline arrangement inside the columns. It is shown that the structure-induced dielectric constant can be consistently explained through first-principles calculations. (C) 1998 American Institute of Physics. [S0003-6951(98)04647-6].