Study On The MgO-TiO₂-ZnO-CaO Microwave Dielectric Ceramics

The MgO-TiO₂-ZnO-CaO (MZTC) system ceramics were investigated in theresearch, which base on the MgO-TiO₂-ZnO system and can be developed as filtersand resonators applied in the microwave frequency area. The MZTC system ceramicsgive excellent microwave dielectric properties with a lower sintering temperature thanthat of the MgO-TiO₂-ZnO system. The effects of the compositions and processingconditions to the dielectric properties of the system were the emphases of this study.The microcosmic mechanism of the system was also discussed in detail by severalmeans.The analysis results of XRD show that MgTiO₃ and ZnTiO₃ formed no-limit solidsolution (Mg,Zn)TiO₃, the lattice constants of which were slightly increased aftersintering. That's due to the Zn²⁺ ions' moving from the grain boundary to the crystalgrain. The formation of the solid solution of MgTiO₃ and ZnTiO₃ lowers the sinteringtemperature needed to densify the ceramics. CaTiO₃ was added to increase thedielectric constant, reduce the loss value and compensate the temperature coefficientof (Mg,Zn)TiO₃. A near zero temperature coefficient can be obtained by adjusting thecontent of CaTiO₃. , which is helpful to improve the dielectric properties. The phasecomposition of the system also changes during the sintering, Mg2TiO4 and rutilesynthesized MgTiO₃, and Mg2TiO4 disappeared finally. ZnO promoted the sintering ofthe ceramic and improved the dielectric properties as a kind of necessary fluxingagent. The microwave dielectric ceramics with superior dielectric properties gained inthis study gives excellent dielectric characteristics as the follows: Measured as capacitor at 1MHz:ε=22±2?c = 0±30ppm/℃tanσ ≤5×10-5Measured as resonator at 7.23GHz:ε=22±2Qf0 =69000Ï„f =5ppm/℃...