Study On Low Temperature Sintering And Microwave Dielectric Properties Of Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄Ceramics

With the growing demand for electronic products with small size, light weight, morefunctions and high integration, it has become a research hotspot to design and fabricatemicrowave components by using LTCC （low temperature co-firing ceramic） technology. Inorder to meet the requirement of reducing the size of microwave components （such asdielectric resonator, filter, oscillator）, it is essential to use microwave dielectric materialswith higher dielectric permittivity as the key materials. Consequently, it is of greatsignificance for production of small-sized and high-quality microwave components toresearch into low temperature sintering and microwave dielectric properties of ceramics withhigh dielectric permittivity.The Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics exhibit high dielectric permittivity of51, a Q×fof26600GHz and acceptable τfof70ppm/°C. Considering that they have a high sinteringtemperature, which means that they can not be sintered with Ag （Cu） electrodes, it isessential to reduce its sintering temperature. In this paper, the effects of additives onsintering temperature and microwave dielectric properties of Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics have been investigated. The phases and microstructure have been surveyed usingX-ray diffraction （XRD） and scanning electron microscopy （SEM）, and the microwavedielectric properties have been measured by an Advantest network analyzer.Firstly, CuO was used as sintering aid to lower the sintering temperature ofZr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics in this paper. The results show that the CuO can obviouslypromote the densification of Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics without impairing thedielectric properties, and also reduce its sintering temperature from1170to1025°C. TheZr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics with the addition of5.8wt.%CuO sintered at1025°Cpossess excellent microwave dielectric properties of εr=44.1, Q×f=11487GHz and τf=62ppm/°C. Stable microwave dielectric properties were obtained in Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics sintered from1050°C to1000°C.Then the mixture of CuO-H₃BO₃was used as sintering aid to lower the sinteringtemperature of Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics which were prepared by solid-state reaction method. Effects of the additives on sintering temperature and microwave dielectricproperties of Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics were investigated as well. The results showthat the mixture reduced the sintering temperature of Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics from1170to920°C. The Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics with the addition of4wt.%CuO+4wt.%H₃BO₃sintered at920°C possess excellent dielectric properties of εr=45.8Q×f=10978GHz and τf=45.6ppm/°C. Moreover, stable microwave dielectric properties wereobtained in Zr_0.3(Zn_1/3Nb_2/3)_0.7TiO₄ceramics with the addition of4wt.%CuO+x wt.%（x=1，2，4）H₃BO₃at the temperature from960to920°C.