Low-temperature synthesis of fully crystallized spherical BaTiO3 particles by the gel-sol method

The synthesis of spherical BaTiO3 particles was attempted by a new technique, the "gel-sol method," at 45degreesC. The (Ba-Ti) gel used as a starting material was prepared by aging mixtures of titanyl acylate with a barium acetate aqueous solution ([glacial acetic acid (AcOH)]/[titanium isopropoxide (TIP)] = 4, [barium acetate]/[TIP] = 1) at 45degreesC for 48 h. Potassium hydroxide (KOH) was used as a catalyst for the formation of BaTiO3. Powder X-ray diffractometry (XRD) results and Fourier-transform infrared (FT-IR) measurements for the (Ba-Ti) gel showed that the gel was amorphous, but the spatial arrangement of barium and titanium in the (Ba-Ti) gel is similar to that in crystalline BaTiO3 particles. Fully crystallized spherical BaTiO3 powder with a particle size of 40-250 nm formed at the very low reaction temperature of 45degreesC. Scanning electron microscopy images showed that the final particles formed via aggregation of the fine particles that seem to be the primary particles of bulk (Ba-Ti) gel. From the XRD, FT-IR, and Raman spectroscopy analysis, it was found that the crystal structure of the as-prepared particles continuously transformed from cubic to tetragonal as the calcination temperature increased, and high crystalline tetragonal BaTiO3 phase was obtained at 1000degreesC after 1 h of heat treatment.