Preparation And Characterization Of Barium Titanate Nano Powder By Hydrothermal Method

Cubic and Tetragonal Barium Titanate micro nano powders with rounded cubic shape were synthesized by hydrothermal method using Ti O₂ and Ti(OC₄H₉)₄ as titanium source respectively,Ba(OH)₂·8H₂O as barium source,mixed solution of water and ethanol as solvent,ammonia water as mineralizer.The influences of molar ratio of barium and titanium,volume ratio of alcohol and water,phase and powder properties,hydrothermal temperature and hydrothermal time on the morphology were systematically analyzed by XRD,SEM and other characterization methods.Results show that cubic phased barium titanate can be synthesized when Ti O₂ is used as titanium source and water is used as solvent.But cubic and tetragonal mixed phase powders can be prepared when the mixture solution of alcohol and water is used as solvent.Increasing hydrothermal temperature and prolonging hydrothermal time can promote the transformation of barium titanate from cubic phase to tetragonal phase.The best conditions for synthesizing tetragonal phase are:alcohol/water=1:1,barium/titanium=1.5:1,hydrothermal temperature is200?and the hydrothermal time is 48 h.Under these conditions,the ration of c and a of the obtained barium titanate is 1.00745 and the tetragonal phase powder content is as high as 75%.When Ti(OC₄H₉)₄ is used as titanium source,the tetragonal phase barium titanate powder content is significantly increased.When the ethanol content is 25%,barium/titanium=1.5:1,the hydrothermal temperature is 200?,and the hydrothermal time is 24h,Barium titanate powder with C/a=1.00839 and tetragonal content as high as 88%can be obtained.The average particle size is 100 With the increase of tetragonal phase content,the morphology of barium titanate powder tends to round cube shape;in the reaction process,the participation of ethanol can not only promote the transformation of Tetragonal Barium titanate,but also increase the pressure in the reactor,so that the morphology of the synthesized powder is more complete and uniform;The formation of barium titanate grains is mainly due to the combination of Ostwald ripening and dissolution precipitation mechanism.