Study On The Preparation And Properties Of CCTO Dielectric Ceramics With Low Loss

CaCu₃Ti₄O₁₂?CCTO?dielectric ceramics have become a research hotspot in the field of dielectrics recently because of its high dielectric constant and good temperature stability.However,due to its high dielectric loss,CCTO ceramics are limited to be put into production and application.Therefore,in order to reduce the dielectric loss of CCTO ceramics,the preparation method based on sol-gel method is adopted in this paper.The best process method for preparing CCTO ceramics is studied,and the dielectric loss is further decreased by doping modification.The main research contents and results are as follows:?1?The effects of different pressing pressure,sintering temperature and cooling methods on the dielectric properties of CCTO ceramics were studied.The optimum pressing pressure is 28–30 MPa.The reason is that higher pressing pressure will lead to smaller porosity of CCTO ceramic.The optimum sintering temperature is 1050–1060?.Higher sintering temperature is conducive to grain growth,but higher temperature will lead to thinner grain boundary and abnormal grain morphology.When CCTO ceramics are quenched in air after sintering,the dielectric loss of the samples decreases by 60%and the breakdown field increases by 20%compared with the samples cooled in furnace.The reason is that quenching reduces oxygen vacancy concentration,increases grain boundary resistance and grain boundary barrier height.?2?The effects of halogen doping on the dielectric properties of CTO ceramics were studied.The dielectric properties of CCTO ceramics can be improved by adding anions.When the doping amount of F element is 0.5,the sample loss decreases to 0.023,which is due to the increase of grain boundary resistance and the decrease of oxygen vacancy.At the same time,the breakdown field strength of CCTOF0.5 ceramics has been greatly increased,resulting in an increase of energy storage density of more than 10 times,which is due to the increase of grain boundary barrier height.The dielectric loss of CCTOBr0.5 ceramics also decreased significantly to 0.019,but the breakdown strength of CCTOBr0.5 ceramics was not significantly different from that of pure CCTO because of the unchanged height of grain boundary barrier.?3?The effects of F and Zn co-doping on the dielectric properties of CCTO ceramics were studied.The dielectric constant can be significantly improved by adding Zn element into CCTOF0.5 ceramics.The reason is that Zn element can promote the grain growth of samples.Another reason is that the extranuclear electrons of Zn²⁺ions are more active than those of Cu²⁺,resulting that the electron relaxation polarization is easy to occur and the dielectric constant is improved.At the same time,the breakdown strength of CCTOF0.5Zn0.2ceramics also increased slightly.?4?The effects F and Ti co-doping on the dielectric properties of CCTO ceramics were studied.The dielectric properties of CCTO ceramics with excessive Ti will be greatly improved.When the excess of Ti element is 0.2,the dielectric loss of CCTOTi0.2 ceramics decreases to 0.020,and the breakdown strength is obviously improved.The dielectric loss of CCTOF0.5Ti0.2 samples co-doped with F and Ti elements has been further reduced,reaching the very low value of 0.015.