Bi₄Ti₃O₁₂ Particles Size Influence on Electrorheolocical Response

Abstract

Electrorheological uids (ER) are commonly known as suspensions composed of semiconducting particles dispersed in insulating oil that respond to electric fields by gelling. The increase in suspension viscosity on application of the field is typically rapid and reversible and as a result, the ER response is amenable to applications where real time control of stress transfer properties is required. Ferroelectric particles are interesting in this application due to the presence of spontaneous polarization and high dielectric constant. Particularly, Bismuth Titanate (Bi4Ti3O12 - BIT) is well-known as layer-structured ferroelectrics, so the typical morphology of these crystals is lamellar. Therefore, these particles dispersed in oil, in the presence of an electric field must produce an interesting ER response. Thus, BIT powders were prepared by the conventional solid state reaction method and the particles size was adjusted using ball milling process. Different ER fluids containing average particles size about 2.5 to 0.5 μm were dispersed in silicon oil about 10% vol and were submitted to AC and DC electric field. The relation between the BIT particles size with the ER response was observed, presenting an increase of the shear stress with the reduction on particle size.