Preparation of nano-sized BaTiO₃ particle by citric acid-assisted spray pyrolysis

Nano-sized BaTiO₃ particles were prepared by citric acid (CA)-assisted spray pyrolysis. It was found that controlling the spray solution with an organic additive made great differences in the structure and morphology of BaTiO₃ particles during the calcination. High agglomerated particles of irregular shape were produced after the calcination at 1050°C when they were prepared from the nitrate solution without organic additive. In contrast, coarse aggregates consisting of nano-sized BaTiO₃ primary crystallites were obtained when we used the nitrate solution containing an organic additive (citric acid, CA). The coarse aggregates were successfully disintegrated to nano-sized BaTiO₃ particles with narrow particle size distribution after a simple ball-milling process. The use of CA additive also affected the crystallographic behavior of the BaTiO₃ nanoparticles. The CA additive prevented phase separation of barium and produced phase-pure BaTiO₃ particles at the as-prepared state and enhanced the phase transformability of metastable cubic phase to the tetragonal one during calcination. Consequently, BaTiO₃ nanoparticles of about 150 nm with good tetragonality were successfully obtained by simple ball milling the coarse aggregates that were prepared from the CA-assisted spray pyrolysis and calcination at 1050°C.