Study Of ZnNb₂O₆-TiO₂ Composite Microwave Ceramics And Its Application In MLCC

In this paper, the low sintering temperature mechanism and microwave dielectric properties of ZnNb2O6-1.75TiO2 (ZNT) microwave ceramics were investigated. The phase composition and crystal microstructure of ZNT ceramics were analyzed by XRD, SEM,EPMA and EDS. The microwave dielectric properties were tested by Hakki-Coleman opened resonator method. The relationship between microstructure and microwave dielectric properties was also investigated. As-synthesized ZNT microwave dielectric materials could be sintered at low temperature. The ZNT with excellent properties was applied to manufacture multilayer ceramic capacitor (MLCC).1. 2.0wt.%CuO +4.67wt.%2 ZnO·3B2O3·3H2O(CZB) were used as sintering agent in this study, we investigated the phase transition, microstructure and the microwave dielectric properties of MgO-doped ZNT composite microwave ceramic materials. It indicated that the Mg2+ ion easily substituted the Zn2+ to form (Zn,Cu,Mg)Nb2O6, (Zn,Cu,Mg)TiNbO8 and (Zn,Cu,Mg)0.17Nb0.33Ti0.5O2 compounds in ZNT system. The substitution of Mg2+ could reduce the grain size and stable the columbite structure. However, too much Mg2+ should deteriorate the microwave dielectric properties of ZNT ceramics. When y=0.05 and the sintering temperature was 950°C, the ZNT composite ceramics exhibited excellent dielectric properties:εr =35.6, Q×f =16,000GHz (at 5.6GHz) andτf = -10ppm/°C.2. With SnO2 and CZB addition, the ZNT microwave ceramics with excellent dielectric properties could be sintered at 950°C. In this system, the SnO2 could handle the formation of Zn2TiO4 and improve the dielectric properties, especially the Q×f value. Furthermore, the SnO2 could improve the insulating resistance of the ZNT composite materials and promote its application in passive components. With the sintering temperature increasing, theεr andτf values reduced owing to the phase transition and the variation of microstructure. We found that ZNT composite ceramics sintered at 950°C, with CZB and 0.15.wt.% SnO2 addition, exhibited excellent dielectric properties:εr=36.7,τf =-22.6ppm/℃, Q×f=18,172.2GHz.3. As-prepared ZNT composite microwave ceramics could be successfully applied in multilayer ceramic capacitor (MLCC). The relationship between the component design, the technological parameters and the properties of MLCC were investigated. The microstructure and the compatibility of inner electrode with ceramics were analyzed by XRD, SEM and EDS. The electrical properties of MLCC were also tested. The results showed that the MLCC (with high Q design) sintered at 950℃exhibited excellent electrical properties and high reliability.