Synthesis And Characterization Of Ferroelectric BaTi₂O₅Nanoparticles And Grain Oriented Ceramics

Ferroelectric BaTi₂O₅is attractive for high Curie temperature andexcellent dielectric along b axis. It’s hopefully used in high powercapacity. However, as BaTi₂O₅is thermodynamically stable only over anarrow temperature range （1220oC-1230oC）, fabrication of BaTi₂O₅ischallenging. The excellent dielectric properties along b axis makesynthezise textured ceramics essential for applications.In this paperdifferent morphology BaTi₂O₅particles are synthesized by soft chemicalmethod to obtain ceramics with large anisotropic dielectric properties.Single-crystalline BaTi₂O₅nanorods, with length up to2.5m andwidth ranging from100-250nm, are synthesized by a simple molten saltmethod, using BaCO₃and TiO₂as precursors at840℃for5h. TheBaTi₂O₅nanorods grow in the normal direction to the （110） plane, whichis close to the polar b-axis. During green body forming, the shear forcetends to align the BaTi₂O₅nanorods in the plane perpendicular to thepressure, achieving textured ceramics which show significant anisotropyin the dielectric properties.Using a layered titanate, K0.8Ti1.73Li0.27O4, as the initial template,plate-like TiO₂（anatase） partiCles were prepared by in situ topotactictransformation reaction. Using BaCO₃and the plate-like TiO₂asprecursors, in a mixed NaCl-KCl molten salt, BaTi₂O₅platelike particleswere synthesized at840oC for5h in different mixed time and mode. Themolten salt synthesis progressed by the dissolution-depositionmechanism. As the dissolution rate of TiO₂is much lower than that ofBaCO₃in the NaCl-KCl molten salts, the plate-like TiO₂particles reactas a template, so that the resulting BaTi₂O₅particles retain the plate-likemorphology of the TiO₂precursors. During green body forming, BaTi₂O₅particles tend to grow along the direction of plate-like TiO₂, achievingtextured ceramics which show significant anisotropy in the dielectricproperties. In summary, different morphologies of BaTi₂O₅particles wassynthezied by soft chemical method successfully and the dielectricproperties of the BaTi₂O₅ceramics differed significantly which laid asolid foundation for future research in the grain preferred orientationBaTi₂O₅ceramics.