Preparation and dielectric properties of dense barium titanate nanoparticle accumulations by electrophoresis deposition method

Dense barium titanate (BaTiO₃, BT) nanoparticle accumulations were prepared by an electrophoresis deposition (EPD) method using three kinds of BT nanoparticles with different particles sizes and tetragonality. First, the BT particles were dispersed into ethanol using ball-milling technique, and an optimum milling condition was investigated. As the results, it was confirmed that ball-milling led to a formation of mixture between single-dispersed nanoparticles and aggregated particles. Thus, the aggregated particles in the slurry were removed by a centrifuge in order to obtain narrow the size distribution. Using well-dispersed slurry, BT nanoparticle accumulations were deposited on paradigm electrode by the EPD method. Despite various BT nanoparticles, the dense BT nanoparticle accumulations were obtained at relative densities of around 60 %. After gold electrode deposition on the both surfaces of the accumulations by spattering method, dielectric properties were measured at 20 °C, the highest dielectric constants of around 160 was measured at 10 MHz.