Synthesis of barium titanate powders by aerosol pyrolysis of a Pechini-type precursor solution

A Pechini-type precursor system, utilizing Ba-nitrate and Ti-isopropoxide with citric acid (CA) and ethylene glycol (EG), has been investigated for the synthesis of BaTiO3 powders using aerosol pyrolysis. Powder produced at 350 °C in the aerosol process had subsequent thermal decomposition (TGA/DTA) behavior that was similar to that reported for the barium titanyl citrate complex BaTi(C6H6O7)3·xH2O, indicating that the short process time and rapid droplet evaporation limit substantial polyester network development in the aerosol process. Crystalline phase development proceeded rapidly at reactor temperatures between 600 and 700 °C. Small amounts of the intermediate phases Ba2Ti2O5CO3, BaCO3 and Ba(NO3)2,were present as impurities in powder produced at 700 °C, and phase-pure BaTiO3 was produced at temperatures above 800 °C. In contrast, a precursor solution utilizing acetic acid as peptizing agent led to a significant amount of nonstoichiometric BaTi2O5, highlighting the importance of the multidentate complexation of citric acid. Dimpled or slightly collapsed hollow particles were typically produced using the Pechini-type precursor. It was demonstrated that the polymeric additives polyethylene glycol and methylcellulose could be used to alter particle morphology without impacting product phase-purity.