| Bi2(Zn1/3Nb2/3)2O7(β-BZN) materals is the monoclinic pyrochlore structure have been paid more and more attraction for low sintering temperature and good dielectric property . However, their dielectric property and dielectric mechanism should also be reserached .the monoclinic pyrochlore microwave ceramics were prepared by traditional solid phase reaction, The effect of A-site,B-site and (A,B)-site substitution on dielectric properties of BZN ceramics was investigated. The effect of oxygen vacancies on dielectric properties of BZN ceramics,the phase transition and mechanism of modification were studied.(1) The sintering temperature of Nd3+,Dy3+,Er3+ substituting for Bi3+ in A-site of Bi2(Zn1/3Nb2/3)2O7 ceramics is 1000℃, The sintering temperature of Y3+,Li+ substituting for Bi3+ in A-site of Bi2(Zn1/3Nb2/3)2O7 ceramics is 960℃. The dielectric properties are:εr=70～90,tanδ=6.3×10-4～6.8×10-3,αc=186～359ppm;the peak of dielectric losses relaxation of Li substituted sample moved towards high-temperature with the increasing of substituted content (from 0.025 to 0.1).(2) The sintering temperature of Zr4+,Ti4+ substituting for Nb5+ in B-site of Bi2(Zn1/3Nb2/3)2O7 ceramics is 1000℃, The sintering temperature of Sn4+ substituting for Nb5+ in B-site of Bi2(Zn1/3Nb2/3)2O7 ceramics is 1020℃,The dielectric properties are:εr=70～90,tanδ=8.1×10-4～2.9×10-2,αc=-240p～448ppm; the peak of dielectric constant relaxation of Sn substituted sample moved towardslow-temperature with the increasing of substituted content (from 0.1 to 0.16).(3) The sintering temperature of Y3+,Sn4+ substituting for Bi3+ and Nb5+ in A,B-site of Bi2(Zn1/3Nb2/3)2O7 ceramics is 1000℃, The sintering temperature of Li+,Sn4+ substituting for Bi3+ and Nb5+ in A,B-site of Bi2(Zn1/3Nb2/3)2O7 ceramics is960℃, The dielectric properties are:εr=74～90,tanδ=7.7×10-3～2.3×10-2,αc=117～377ppm; the peak of dielectric constant relaxation of Li+,Sn4+ substitutedsample moved towards low-temperature with the increasing of substituted content(from 0.025 to 0.1). |
