Technical Study On The Preparation Of Barium Titanate Nano-powder

BaTiO3(BT)nano powder with good dispersion was prepared via precipitation and non-hydrolytic sol-gel method by using barium acetate and titanium tetrabutoxide as precursors.The phase transition of BT xerogel during the heat treatment was studied.The effects of the precursor concentration,complex solvent ratio,the dosage of chelator and precipitant,dosage and adding time of PEG 1000 and heat treatment on synthesis and dispersion of BT powder have been investigated by DTA-TG,XRD,FT-IR and TEM analysis when BaTiO3 prepared via precipitation method.Meanwhile,the effects of the barium source,the kinds of solvents,precursor concentration,complex solvent ratio and heat treatment on synthesis and dispersion of BT powder have been studied via when BaTiO3 prepared non-hydrolytic sol-gel method.The experimental results indicated that:When BT nano powder prepared via precipitation method,the appropriate precursor concentration is 0.8 mol/L,overlow precursor concentration is can not synthesize pure BT phase,overhigh precursor concentration leads to agglomeration.The appropriate molar ratio of acetylacetone and titanium tetrabutoxide is 1:1,when the molar ratio more than 1:1,it can not synthesize pure BT phase because of too fast hydrolysis rate of titanium tetrabutoxide,when the molar ratio less than 1:1,pure BT can be synthesized,but there is no significant improvement of the morphology.The optimal molar ratio of urea and titanium tetrabutoxide is 4:1,it cause impurity phase if urea insufficient.The appropriate heat treatment temperature is 750? for 2 hours,overlow and overhigh heat treatment temperatures are both not beneficial to the preparation of BT nano powder.In this process,adding 2.0 wt.%PEG 1000 can alleviate the powder aggregation and the average particle diameter is about 20 nm.When BT nano powder is prepared by non-hydrolytic sol-gel method,the appropriate barium source is barium acetate,it can not be synthesized BT powder at 650? by using barium chloride as barium source,because the electronegativity of barium is small,and the electronegativity of chloride is high,the formation of barium chloride is ionic compound,the de-alkyl halide reaction between barium chloride and titanium tetrabutoxide can not occur.Complex solvents of ethanol and glycerol is the appropriate solvent.BT naono powder can not synthesis at 650? when acetic acid is used as solvent,because acetic acid is a strong Lewis acid which can catalyze homogeneous polymerization.The dispersion of BT nano powder prepared with ethanol and glycerol as complex solvents is better than that of BT powder prepared with glycerol as single solvent.The optimal BT powder with the particle size of 20 nm and well dispersion can be prepared when the precursor concentration is 0.4 mol/L,ethanol and glycerol are used as complex solvents,the volume ratio is 4:1,with refluxing at 110?for 24 hours and calcining of 650?.