Synthesis of ultrafine and spherical barium titanate powders using a titania nano-sol

A novel synthetic method for the preparation of spherical, homogeneous, and ultrafine barium titanate (BaTiO3) powders is described. An aqueous titania nano-sol was prepared by peptizing coarse aggregate of hydrous titania with nitric acid. BaTiO3 powders could be synthesized through a simple reflux method using the titania nano-sol and barium hydroxide. As decreasing the titanium concentration, the particle size of the resulting spherical BaTiO3 powder was increased from 40 to 130 nm and the porosity also increased. It was revealed that the smaller as-prepared BaTiO3 powder was less porous and became more tetragonal with less intragranular pores after annealing. With this method, a highly tetragonal BaTiO3 powder (c/a similar to 1.008) with a particle size of 120.0 nm was successfully prepared and would be very suitable for the thinner dielectrics in higher capacitance multilayer ceramic capacitors.