Ltcc Znnb <sub> 2 </ Sub> O <sub> 6 </ Sub> Based Microwave Dielectric Ceramics Preparation And Research

ZnNb2O6 microwave dielectric ceramic is developed in recent years. It exhibits moderate dielectric constant, high the quality factors (Qxf) and adjustable temperature coefficients of resonant frequency. Due to the high sintering temperature (1200℃), it is difficult to realize co-fired with Ag or Cu. So it is essential to investigate its characteristics and low-temperature sintering. With the general review of low-temperature sintering microwave dielectric ceramic and the research of the authors on microwave ceramic, the effects of sintering aids on the properties of ZnNb2O6 microwave dielectric ceramic and the low-temperature sintering of ZnNb2O6 microwave dielectric ceramic were investigated.The ZnNb2O6 microwave dielectric ceramic was used as studied object. It was prepared by conventional mixed solid method. The effects of different sintering aids on sintering characteristics, phase compositions, microstructures and dielectric properties of ZnNb2O6 microwave dielectric ceramic were studied systematically X-ray diffraction (XRD), scanning electron microscope(SEM), microwave dielectric measurement were used as analysis methods.The ZnNb2O6 ceramic which doped B2O3 had well dielectric properties, temperature coefficients of resonant frequency improved and on second phase appeared. The samples of ZnNb2O6 with lwt% B2O3 sintered at 1050℃for 4h exhibit excellent dielectric properties:εr=24.1, Qxf=19502GHz,τf=-52.19ppm/℃. The ZnNb2O6 ceramic which doped CuO had some new phase such as Zn3Nb2O8 and a small quantity of Cu0.5Zn0.5Nb2O6 except the main niobite phase. The additive of CuO made the quality factor go to bad and temperature coefficients of resonant frequency improved. The samples of ZnNb2O6 with lwt% CuO sintered at 1050℃for 4h exhibit excellent dielectric properties:εr=23.87, Qxf= 17750GHz,τf=-54.38ppm/℃. Doped with low softening of ZBS glass, the sintering temperature of ZnNb2O6 ceramic sintering temperature can be effectively reduced from 1200℃to 950℃,which is better than B2O3 or CuO. The samples of ZnNb2O6 with lwt% ZBS sintered at 950℃for 4h exhibit excellent dielectric properties:εr=23.56, Qxf= 19681GHz,τf=-58.54ppm/℃. The samples of ZnNb2O6 with 3wt% BCB sintered at 875℃for 4h exhibit excellent dielectric properties:εr=23.4, Qxf= 13230GHz,τf=-78.41ppm/℃The line-scanning of sample results indicate that no evident diffusion was happened, it has a good conjoint status and chemical compatibility between ceramic and Ag electrode. It can be used as a new kind of LTCC microwave dielectric ceramic multilayer chip for production of electronic components.