Effects Of Rare Earth Element Doping On Dielectric Properties Of Bzt-based Ceramics

Ba Ti O3 and its solid solution with perovskite type structure material is the important material for preparation of multilayer ceramic capacitors. By adding the other elements into Ba Ti O3 system, its microstructure was changed, so that its dielectric properties was improved for meeting practical application.Ba Zr0.1Ti0.9O3 based ceramics powder modified with Dy2O3, Nd2O3, Y2O3 and Ca O were prepared by the solid reaction method, and BZT based ceramics powder was coated by Al2O3 with wet coating method. The volume density of sample was tested based on the Archimedes drainage method; the phase composition and the crystal structure of the sample wih burning were tested by XRD; the surface and cross-section morphology of the sample were observed by SEM; the dielectric properties of sample were determined by capacitance measuring instrument. The research results showed as follows:With invreasing blending ratio of Dy2O3, the εr gradually increased, the tanδ was slightly increased but then decreased. With the doping amount of Nd2O3 increasing, the εr rised slightly. When the doping amount of Nd2O3 was small, tanδ of the sample went up significantly, and then as the Nd2O3 increased, the tanδ dropped.When the doping amount of Y2O3 was 0.05mol%, tanδ droped to the lowest value, the εr was between 2032~2168, the εr gradually rised with the amount of Y2O3 increasing. As the system increased the amount of Ca O, the εr increased and the tanδ changed with the doping amount of the sample exhibits a nonlinear relationship, the dielectric constant decreased with the rate of temperature changed, and the Curie peak moved to a lower temperature.With the increasing amount of Al2O3 coating, the εr gradually reduced, while the tanδ gradually increased, the rate of capacitance change △C/C gradually decreased, and the Curie peak shifted to lower temperature.