Preparation And Research Of The Barium Titanate-based And NiO-based Materials Of High Dielectric

High dielectric materials are key materials for the electric capacitors with high energy density and the super-capacitors for electric-energy storage equipments.Among several kinds of high dielectrics,barium titanate based ceramics and NiO based ceramics attract many researchers attention.Barium titanate and its doped derivatives have high dielectric constant and very low dielectric loss,but have poor temperature stability.Doped-NiO and related materials have have very high dielectric constant,but have high dielectric loss.In this study,multi-doped barium titanate ceramic materials were synthesized with three different methods,and the effect of the preparation method and the raw materials was investigated on the structure and the dielectric properties of the materials.Doped and codoped NiO ceramics was also synthesized with solid state method,and the effects of dopants,as well as the coating with SiO2 were investigated on the structure and the dielectric properties of the materials.The results show that single phase multi-doped barium titanite samples(BCNTZYM)with tetragonal structure can be synthesized by all three methods when the calcining temperature is not lower than 1250?.The sample synthesized with the low cost sol-gel method has the highest dielectric constant which reaches 8000 at room temperature.Ba1-xSrxTiO3 materials show higher dielectric constant when singly doped with Yor Nb than codoped with Y and Nb.The dielectric constant of La doped Bai1-xSrxTiO3 materials changes with the doped amount,and reaches the highest(8000)at 0.11 atm%.The NiO-based ceramics synthesized at 1100? show the highest dielectric constant of 17000 which is independent of temperature.