Behavior of barium acetate and titanium isopropoxide during the formation of crystalline barium titanate

The behavior of Ba and Ti sources in the reaction mixture during the formation of crystalline barium titanate (BaTiO3) powders from titanium isopropyl alkoxide (TIP)/acetic acid/barium. acetate/KOH solutions has been investigated. From Fourier transform infrared (FT-IR) analysis, it was found that two acetate groups per Ti atom participate in TIP modification and titanium oxo bridges (Ti-O-Ti) are generated by the alcohol and isopropyl acetate forming condensation reaction. The low dissociation constant of barium acetate in the strong alkaline aqueous solution is responsible for the formation of nonstoichiometric BaTiO3 particles when the molar ratio of barium acetate to TIP is equal to 1 in reaction mixtures. From FT-IR and X-ray diffraction analysis of as-prepared powders and pure barium acetate, it was found that barium oxalates, barium carbonate, and potassium carbonate intermediate phases were formed during the thermal treatment of as-prepared powders because of the decomposition of unreacted pseudo barium acetate phases coexisting in as-prepared powders. The pseudo barium acetate is needlelike and easily removed by washing. Pure crystalline BaTiO3 powders were obtained by calcination at 900 degreesC for 1 h. Because of the nonhomogeneity of as-prepared particles, the crystallinity of BaTiO3 particles calcined at 900 degreesC decreased with increasing molar [AcOH]/[TIP] ratios.