New Ultra-high Permittivity High Frequency Heat-Stable Medium-Temperature Sintering Ceramic Material

The high frequency system with ultra-high permittivity was studied in this paper. Based on dielectric physics, material physical chemistry, crystal chemistry and coordination chemistry, surface and interface chemistry, the modern analysis method XRD,TEM,EDX,SEM,DTA-TG,IR spectrum method were used in the this paper. High frequency system Ag(Nb,Ta)O3 and(Ag1-xNax)(Nb1-yTay)O3 were systematically investigated in China. As compared with the solid synthetic method, wet-chemical synthetic method was applied to synthesize ANNT system stoichiometrically in order to improve the dielectric properties of the system. The structure and dielectric properties of ANT system were analyzed in detail. At same time, the relationship between structure and dielectric properties was discussed thoroughly. The high frequency temperature-stable system was obtained by adjusting Nb/Ta ratio and synthesizing precursor in advance.The effects of dopants Bi2O3,Sb2O5,MnO2 and glass phase on the properties of the ANT and ANNT system were investigated. It suggested that proper doping could improve the sintering properties and dielectric properties of the system.The investigation indicated that dielectric loss resulted from the relaxation polarization of B-site Nb5+ ion. The lattice parameter would decrease when the A-site Ag+ ion was substituted partly with Na+, so the volume of oxygen octahedron would decrease correspondingly, which would depressing the relaxation polarization of the system.The ANNT system was synthesized by liquid state method. Contrastively, the influence of synthesis methods, citrate method and oxalate method, were investigated. The outcome was that oxalate method lead to agglomeration much more than citrate method did. The particle prepared by citrate method distributed uniformly and the average particle diameter, which was about 40nm, was smaller. The average grain diameter of ceramic produced by citrate method was 0.5μm, so the dielectric properties were improved.The dielectric data of the system prepared by solid state method are as follows:Dielectric constant ε ＞400Temperature coefficient of capacitanceαc ＜0±30ppm/℃Loss tangent δ ＜10×10-4Insulation resistivity ρv ＞1012Ω·cmSintering temperature Ts 1050℃～1160℃ The dielectric data of the system prepared by solid state method: Dielectrics constant ε ＞500Temperature coefficient of capacitanceαc ＜0±30ppm/℃Loss tangent δ ＜10×10-4Insulation resistivity ρv ＞1012Ω·cmSintering temperature Ts 1050℃～1160℃...