Niobium Zinc Microwave Dielectric Ceramics Preparation And Structure And Dielectric Properties

Zinc niobates microwave dielectric ceramics have been widespread paid attention to as a kind of microwave medium material with good potential application for good dielectric properties and inherent, low sintering temperature. In this paper, zinc niobates microwave dielectric ceramics were prepared by different ways and the ceramics formation process was studied.Zinc niobates microwave dielectric ceramics were prepared by the traditional solid-phase method, and then the temperature of phase formation was ascertained. We find the Zn3Nb2O8 ceramics were prepared at 1100℃while the ZnNb2O6 ceramics were prepared at 1000℃by the traditional solid-phase method. We analyzed the dielectric properties of Zinc niobates ceramics prepared by traditional solid-phase method at low frequency (fn=30MHz):the relative density of the Zn3Nb2O8 ceramics sintered at 1200℃for 4 hours was 96.82%, thewas 22.10. The relative density of the Zn3Nb2O8 ceramics with CVB 1.5wt% sintered at 1000℃for 4 hours was 94.42%, theεr was 20.02. The relative density of the ZnNb2O6 ceramics sintered at 1100℃for 4 hours was 93.41%, theεr was 17.88.We definite the preparation technology of soluble niobium salt:the reaction temperature and pH range of zinc niobates microwave dielectric ceramics prepared by chemical co-precipitation method were ascertained according to thermodynamics and niobium salt dissolution experiments. Through niobium salt dissolution experiments, we find that dissolution rate of Nb2O5 was up to 92.59% under n(KOH)/n(Nb2O5)=10:1,450℃×4h melting reaction. At room temperature, the reaction pH ranges from 8 to 11 while the reaction pH ranges from 7.5 to 10.5 at 70℃.A series of zinc niobates microwave dielectric ceramics powder was prepared by chemical co-precipitation method. Formation process and mechanism of zinc niobates microwave dielectric ceramics have been studied. We studied some factors, such as pH and temperature, affect the preparation of Zn3Nb2O8 ceramic powder. The phase structures of precursor and the calcined ceramic powder were analyzed through XRD. Particle size was analyzed by Laser Particle Size Analyzer. Sintering temperature of the ceramic was decided by TG-DTA. SEM was used to analyze the morphology of ceramics. The results showed that:The zinc niobates precursor powder calcined at 600℃shows good phase structure. Powders with n(Zn)/n(Nb)=2.8:2, calcined at 850℃, have the same XRD diffraction with the Standard spectrogram of Zn3Nb2O8. The precursor prepared at n(Zn)/n(Nb)=0.7:2 would form ZnNb2O6 ceramic powder while calcined at 750℃. We analyzed the dielectric properties of Zinc niobates ceramics prepared by chemical co-precipitation method at low frequency (fn=30MHz):the relative density of the ZnNb2O6 ceramics sintered at 950℃for 4 hours was 88.62%, theεr was 10.09. The relative density of the ZnNb2O6 ceramics with CVB 1.5wt% sintered at 950℃for 4 hours was 94.20%, theεr was 19.83. The relative density of the ZnNb2O6 ceramics sintered at 950℃for 4 hours was 95.34%, theεr was 24.46.