Preparation And Characterization Of Barium Titanate Ceramic Powders By Sol-hydrothemal Method

Barium Titanate (BT) nanopowders with perovskite structure were successfully prepared by asol-hydrothermal method. The influence of alkalinity on the particle size are of particularimportance.By comparing the traditional hydrothermal method and the rotating ones, the particlefabricated by Rotating hydrothermal method exhibit better crystallinity than the one by directhydrothermal method, thus effectively facilitating crystallization and dispersion of the final product.At1.0M alkalinity, BT powders in size of80nm by the Rotating hydrothermal method were evenlydispersed with no aggregation.Monodispersed perovskite-type BT crystallites through hydrothermal treatment at200°C for16h were successfully prepared by varying the synthetic conditions. The final hydrothermal BT powdersare composed of a simple cubic perovskite structure at alkalinity below0.5M, whereas the tetragonaltend to form at higher alkalinity. The reduction of defects within the crystal lattices is responsible forthis transformation from cubic to tetragonal. The morphologies of BT particles evolved from smalland irregular shapes to circular or rectangular shapes with increasing alkalinity. A supposed formationmechanism, namely, the improvement of Ba/Ti ratio derived from elevating the alkalinity that reducesthe impurities adsorbed on the surface of nanocrystals, thus facilitating the alignment and coalescenceof building blocks with the same crystal axes, is successfully utilized to elucidate this transformation.The method utilized in this study to fabricate BT powders with tunable morphology and crystal formis general, and could be extended to synthesize other functional materials.In addition, the influence of hydrothermal temperature, time and solvent on the product wasinvestigated. The reaction temperature and time have a strong influence on the particle phase andmorphology of BT. The particle size increases with an increase of the reaction temperature. Thetetragonal phase content increases and an individual particle finally transforms from an aggregate to aperfectly single particle with increasing reaction time. With the increase of the content of IPA,crystalline of product increases and morphology varies. rod-structured product was obtained when theIPA content is50%.The barium titanate ceramic composed of powders by hydrothermal sol-gel method was prepared,and the microscopic properties were also investigated. The impact of different sinteringtemperatureson surface morphology and properties of barium titanate ceramics was studied. It isindicated that with the increasing sintering temperature, the performance of the barium titanate ceramic was improved, and the surface is denser. Barium titanate ceramics sintered at1300℃posessed the highest dielectric constant of2487, and a smaller dielectric loss of0.013. Compared tothe non-annealed barium titanate ceramics, the dielectric constant of the annealed barium titanateceramics increase.