Study On Processing And Dielectric Properties Of SrTiO₃ Based Ceramics For High Energy Storage

Strontium titanate(SrTiO3) is a important dielectric material with ABO3-type cube perovskite structure at room temperature, It's curie temperature is-250℃. Compared with BaTiO3 and TiO2, SrTiO3 has relatively high dielectric constant and relatively high breakdown strength. It has great potential in many fields such as high voltage energy storage. How to improve the dielectric constant and breakdown strength at the same time is the main problem which high energy density dielectric materials are facing. How to improve the dielectric constant and the breakdown strength of the SrTiO3 ceramics is the most important problem we should tackle in order to improve its energy density. This paper is aiming to solve these problems, we hope to improve the dielectric properties and breakdown strength by add rare earth oxide and sintering aid to SrTiO3 ceramics.As a important research method, doping can change the properties of funcional ceramics remarkably. By doping with rare earth oxide, we can improve the densification and dielectric properties of ceramics. At present, ABO3 structure doped with rare earth eletment in A or B site is one of the hotspots. In this thesis, the dielectric properties of strontium titanate ceramics by substituting divalent Sr2+ with trivalent Dy3+were investigated.This paper investigated the effects of rare earth oxide Dy2O3 addition on microstructures and electrical properties of SrTiO3 ceramics by solid state method. The crystal structure and microstructure of ceramics were analyzed by XRD,SEM. The results show that, when x≦ 0.03 a single-phase structure was obtained, and when x=0.04 the second phase was found from the XRD patterns. At frenqucy 1kHz, the dielectric sonstant value of the samples increased from 309 to 2506 with the x increased from 0 to 0.01, and when x increased to 0.03 the dielectric constant decreased. When x=0.04, the dielectric constant and dielectric loss of the samples increased sharply, which is the result of the existence of the second-phase. With the increasing of x, the breakdown strength of the samples increased first and then decreased.We use ZnO as a sintering aid to improve the dielectric properties of the system and lower the sintering temperature. ZnO was added to the Sr0.99Dy0.01TiO3 system and different sintering process was produced. The efftct of ZnO content on the dielectric performances of Sr0.99Dy0.01TiO3 system was studied. The results show that the addition of ZnO has remarkably effects on the dielectric properties of the system. When x=0.7,the excellent properties of the system had been obtained. Sintered in 1320℃for 3h, Sr0.99Dy0.01TiO3+0.7wt%ZnO system exhibited extraordinary dielectric properties:εr=4886, tanδ=4.9%, Eb=8.9kV/mm.