Effect Of Scandium Oxide And Tantalum Oxide Doping On Dielectric And Ferroelectric Properties Of Barium Zirconate Titanate Ceramics

Nowadays,with the rapid development of electronic components,the performance requirements of ceramic capacitors are becoming more and more strict.How to prepare ceramic capacitor materials with excellent dielectric properties and good temperature stability has become a major problem for dielectric ceramic scholars.In this thesis,based on previous research results,the doping modification of ceramics whose main crystal phase chemical equation is Ba(Zr_0.1Ti_0.9)O₃（BZT）was studied,in order to obtain ceramic capacitor materials that meet the requirements of ceramic capacitors for temperature and capacitance change rate and have practical application value.In this experiment,Sc₂O₃,Ta₂O₅and Ba(Zr_0.1Ti_0.9)O₃ceramics co-doped with them were prepared by solid-state reaction method.the microstructure,surface morphology,dielectric properties and ferroelectric properties of the samples were analyzed by means of x-ray diffraction（XRD）,scanning electron microscope（SEM）,energy dispersive spectrometer（EDS）,high and low temperature dielectric property testing system and ferroelectric testing system,and the dopant content and sintering process were studied The results show that when Sc₂O₃and Ta₂O₅are doped with BZT ceramics alone,the ceramic system with low doping composition is tetragonal perovskite structure,and no second phase is formed.When they are co-doped,Ta⁵⁺and Sc³⁺first replace Zr⁴⁺and then replace Ti⁴⁺.With the increase of doping amount,the ceramics change from pseudo cubic phase to tetragonal phase,and multiphase coexists.With the increase of doping composition,Curie temperature of BZT ceramic system shifts to the left,the dielectric constantε_{r RT}at room temperature increases at first and then decreases,and the hysteresis loop changes from"waist-shaped"ferroelectric to"linear"paraelectric.Increasing the doping amount of modifier properly can improve the dispersion phase transition degree of ceramics and enhance the temperature stability of ceramics;Ba(Zr_0.1Ti_0.9)O₃ceramics with high Ta₂O₅content are ferroelectrics with complete dispersion phase transition.The ceramics with better performance can be obtained by proper sintering process,and Ba(Zr_0.1Ti_0.9)O₃-based ceramic capacitor materials with better temperature stability can be obtained by changing the doping amount of modifier under the optimal sintering process.Ceramics meeting the standards of Y5V,Y5U and Y5T ceramic capacitors were prepared by experiments.The room temperature dielectric constantε_{r RT}of Y5V ceramic BZT-4%BTS ceramic is as high as 9743.98,and the room temperature dielectric loss tanδ_RTis 0.0101;the room temperature dielectric constantε_{r RT}of Y5U ceramic BZT-0.8%Ta₂O₅ceramic is 4565.175,and the room temperature dielectric loss tanδ_RTis 0.031,which has great application potential.