Preparation And Dielectric Properties Of Ba (Zr_xTi_1-x) O₃ Powders And Ceramics By Sol-Gel Process

As a high performance ferroelectric materials, Barium Titanate has been developed into anew kind of functional ceramic since Wainer and Selomon found its good dielectricproperties in 1942. But the Tc of Barium Titanate is about 120℃which restricts itsapplication in room temperature. Doped Barium Titanate is the preferred research direction toimprove the dielectric properties of Barium Titanate. In recent years, the research of Ba(Zr_xTi_1-x) O₃ is popular because that the Zr⁴⁺ is much more stable than Ti⁴⁺ and the Tc of Ba(Zr_xTi_1-x) O₃can be shifted into room -temperature.The traditional preparation methods of BaTiO₃ is solid phase synthesis.The Sol-Gelprocess has advantages of low price of raw material, simple equipments, high purity ofpowders, particle size controllable and low sintering temperature. So in this work Ba(Zr_xTi_1-x) O₃ powders was prepared by sol-gel method. The effect of synthetic conditionssuch as pH value and the heat treatment temperature on the crystallization phase wasinvestigated. The crystalloid Ba (Zr_xTi_1-x) O₃ powders were calcined in 750℃.XRDinvestigation confirmed that the powders have the crystalline of the pure cubic perovskitestructure. The temperature of heat treatment is 340℃lower and the time of keepingtemperature is 3h which is shorter than foreign scholars' results.The effect of differentsintering temperature on performance is also discussed. The ceramic sintering in 1340℃isdense and shows a homogeneous distribution of grain size.The results of the dielectric properties analysis showed that the higher Zr content leaded toa higher dielectric constant before x=0.10 of which the peak value was 12491 at X=0.10. Atlarger x, the permittivity maximum broadened, and continued to move to lower temperatures.Relaxation appears with increasing Zr content. The SEM pictures showed that the grain sizedecreased greatly with the increasing Zr content, which was 200-800nm at X=0.10. Dielectricintensity is 25000～31000V/cm which increases with more Zr content.