Study On Dielectric Properties And Impedance Behavior Of BaTiO₃-based Ceramics

Perovskite structure material is a broad categories,contains a lot of more phyletic,the general formula of its molecules to ABO3.BaTiO3 is a typical ferroelectric.It has high dielectric constant,but the temperature coefficient of poor,doped with formation of solid solution to maintain the high dielectric constant and good temperature stability.Barium titanate as matrix,this paper through the different elements of compound doped synthesis of similar compounds of the relaxation body,trying to obtain high dielectric constant and low dielectric loss,at the same time has a good temperature stability and frequency stability good ceramic material.This paper was prepared by conventional solid phase sintering technology of0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃?A=Mg,Zn,Ca,Ba,Sr,Ni,Fe,Cu?lead-free relaxa-tion ceramic material.Polycrystalline of ceramics samples in oxygen atmosphere annealing treatment,in order to explore the influence of oxygen vacancy on the ceramic dielectric properties,revealing the specific process of oxygen vacancy.XRD results show that all ceramic as pure perovskite structure.Using Raman spectroscopy to detect the local structure of the ceramic,Raman peak type,suggests that the local structure is not entirely cubic symmetry.The dielectric spectrum,isothermal dielectric spectrum and impedance spectroscopy analysis the electrical properties and interface characteristics of the ceramic samples,the dielectric properties of the ceramic and the dielectric relaxation of conductive mechanism.The main research results are as follows:?1?0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃?A=Mg,Zn,Ca,Ba,Sr,Ni,Fe,Cu?are completely solid solution,formed A single perovskite structure,no second phase;Radius of ion doping after the formation of the relatively poor material ordered degree,degree of order increase after annealing;In the body of the ceramic material crystal phase there are other crystalline phases of micro area.?2?0.9BaTiO₃-0.1Ba(Ca_1/3Nb_2/3)O₃ has weak dispersion phase transition at low temperature relaxation and high temperature dielectric relaxation.Two kinds of relaxation weakened after annealing,the material ordered degree increase,decrease the oxygen vacancy.?3?oxygen vacancy for ceramic dielectric permittivity,dielectric loss has great influence.0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃ oxygen vacancy to activate each are not identical.In oxygen annealing can effectively reduce the dielectric loss,dielectric constant are generally reduced,however,some also increases,in general,annealing in oxygen atmosphere can improve the ceramic dielectric temperature stability.?4?0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃?A=Mg,Zn,Ca,Ba,Ni,Fe?ceramic samples for the high temperature dielectric relaxation is produced by ionization of oxygen vacancies and transition,the air sintering 0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃?A=Sr,Cu?the high temperature of ceramic dielectric relaxation caused by oxygen vacancy and ion transition.0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃?A=Mg,Zn,Ca,Ba,Ni,Fe?dc conductivity of high temperature ceramic sample is mainly caused the long-range migration of the oxygen vacancy,the air sintering 0.9BaTiO₃-0.1Ba(A_1/3Nb_2/3)O₃?A=Sr,Cu?ceramic high temperature conductivity is caused by oxygen vacancy and ion transition.