Effects of raw materials on nonhydrolytic sol-gel synthesis of Ba0.6Sr0.4TiO3

Abstract

The effects of raw materials on the nonhydrolytic sol-gel synthesis of Ba0.6Sr0.4TiO3 were systematically studied in this work. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM). Ba(CH3COO)2, Sr(CH3COO)2, BaCO3 and SrCO3 can undergo deesterification substitution reaction with Ti(OC4H9)4 to synthesize Ba0.6Sr0.4TiO3 phase. Sample taking Ba(CH3COO)2 and Sr(CH3COO)2 as barium and strontium source has better Ba0.6Sr0.4TiO3 synthesis results than that of samples using BaCO3 or SrCO3. Ba0.6Sr0.4TiO3 phase can not be synthesized at low temperature taking BaCl2, SrCl2 and TiOSO4 as barium, strontium or titanium source due to their strong ionic bonding. TiCl4 undergoes an alcoholysis reaction with (oxygen donor) alcohol to form a multimolecular association structure and solvated complex chlorotitanium alkoxide, which reduces the possibility of a deesterification polycondensation reaction. The Ba0.6Sr0.4TiO3 phase cannot be synthesized at low temperatures when CH3CH2OH or C3H7OH is used as the solvent. The synthesis of Ba0.6Sr0.4TiO3 is insufficient because of the coordination ability and solvation effect when CH3COOH is used as the solvent. The synthesis of Ba0.6Sr0.4TiO3 is the best when Ba(CH3COO)2, Sr(CH3COO)2, Ti(OC4H9)4 and glycerol (C3H8O3) are used as the barium source, strontium source, titanium source and solvent, respectively. Pure Ba0.6Sr0.4TiO3 phase with a particle size of 17–43 nm and high dispersion is synthesized when the molar ratio of barium-strontium-titanium is 0.6:0.4:1.2.