Preparation And Ceramic Properties Of Nano-Sized Barium Titanate Powders By Solid State Method

Barium titanate（BaTiO₃,abbreviated as BT）as an ABO₃ type perovskite compound,which widely used ferroelectric material.It known as the"pillar of the electronic ceramics industry".Due to the continuous development of electronic components to miniaturization,intelligence,high performance,and with the continuous reduction of MLCC size,the thickness of the dielectric layer continues to decrease.So the grain size,square phase content,uniformity,dispersion of BaTiO₃ powder are put forward higher requirements.Due to the hydroxyl defects in the BaTiO₃ powder synthesized by the liquid phase method,which will seriously affect the performance of MLCC.There are still many researchers who are committed to the preparation of small-size,high-quality BaTiO₃ powders by the traditional solid-phase method.In this paper,Ba（OH）₂·8H₂O and H₂Ti O₃ were used as raw materials to prepare nano-BaTiO₃ powders by the traditional solid-phase method.And the dielectric properties of BaTiO₃ ceramics were optimized.The samples were analyzed using characterization methods such as thermogravimetric analyzer,XRD,FTIR,Raman,SEM,XPS,LCR analyzer,etc.The main research work and results are as follows:（1）To improve the purity and particle size distribution of barium titanate powder,the use of a high-energy ball milling method for mixing.Due to the small size of H₂Ti O₃ with high activity,it not need to grind refinement.High brittleness of Ba（OH）₂·8H₂O can be crushed under high-energy ball grinding,so it can be mixed with the help of high-energy ball grinding Ba（OH）₂·8H₂O at the same time.The optimal mixing time for and H₂Ti O₃ is 8h.Ba（OH）₂ has a lower decomposition temperature than Ba CO₃,so Ba atoms can diffuse at low temperatures,H₂Ti O₃ size makes the diffusion rate and reaction efficiency significantly improved.On this basis,calcination temperature,the treatment mode of H₂Ti O₃,barium titanium ratio,insulation time on the product effects were studied.The parameters of the optimized process are:the barium titanate powder with an average particle size of 213 nm and a high tetragonal phase（c/a=1.0092）was prepared at 1000°C for 3 h.（2）Based on the above,the effects of BaTiO₃ powders with different contents of APTES（KH550）on their dispersion and dielectric properties were explored.The results show that KH550 will form a bilayer structure on the surface of barium titanate powder,relying on its steric hindrance effect,improve the dispersion of barium titanate powder.And adjust the dielectric properties of barium titanate ceramics by relying on its characteristics of containing Si elements.The parameters of the optimized process are:the ceramics were prepared at 1275°C for 2 h.It has the best dielectric properties.The dielectric constant at room temperature is 4310 and the dielectric loss is 0.00695 at 10 k Hz.（3）The above-mentioned high tetragonal phase barium titanate powder has high activity due to its small size.So the traditional sintered BaTiO₃ ceramic is easy to leads to the phenomenon of abnormal grain growth.And BaTiO₃ as good absorbing material,can be prepared by microwave sintering ceramics because microwaves are heated in the way of internal vibration of the material so that barium titanate ceramics are heated uniformly so that the internal defects of the ceramics are few and it is not easy to skew the components.The results show that the BaTiO₃ ceramic,which has been microwave sintered at 1100°C for 2 h,has a uniform grain size and less interfacial Ba atom segregation.The dielectric constant at room temperature is 5688 and the dielectric loss is 0.02095 at 10 k Hz.