Dispersion of Nano-sized BaTiO₃ Particles in Toluene-Ethanol Media Using Phosphate Ester

Abstract

An essential requirement for adequate BaTiO₃ suspension is low viscosity at high shear rates for the ease of shaping and a suitable yield stress to maintain the shape after the forming process. The appropriate range of viscosity is reported to be 800–1100 mPa·s at a shear rate of 100 s^-1. Particles need to be in a well-dispersed state to achieve homogenous and fine grain structure in a final sintered product.
Four different kinds of phosphate ester were examined about the role as dispersant for submicro-sized BaTiO₃ particles suspended in toluene-ethanol media. In order to find out the effect of phosphate ester on dispersion state of the suspensions, rheological properties, median size and zeta potential of obtained suspensions were investigated. Oleyl acid phosphate gave the best result as the median diameter of BT-01 is reduced to 0.34 μm in toluene-ethanol media by adding 1mass% oleyl acid phosphate. It is suggested that dispersion enhanced by oleyl acid phosphate is based on steric hindrance due to the large alkyl chain.