Characteristics of BaTiO3 particles prepared by spray-coprecipitation method using titanium acylate-based precursors

BaTiO3 particles of ultrafine size and high crystallinity were produced by a spray-coprecipitation technique. To improve stability, titanium isopropoxide was acylated using acetic acid. The sol solutions were prepared by mixing the titanium acylate with aqueous barium acetate. Spray-precipitation was performed in concentrated KOH solution (pH > 13). Investigated variables were the metal content and Ba/Ti ratio in sol solutions, the reaction temperature and time, and the calcination temperature. BaTiO3 particles were synthesized in an aggregate form composed of tiny spherical, crystalline grains (20-30 nm in diameter). The barium-deficient stoichiometry of resulting particles was closely related to a rather poor precipitation yield of barium ions in KOH solution. Crystalline BaTiO3 phase was formed by two different mechanisms: ion-solid reaction and solid-state reaction. BaTiO3 particles, in purely cubic phase as synthesized, underwent a phase transition to tetragonal phase by calcination over 500 degrees C.