Microwave Dielectric Properties Of MNb₂O₆-ZrTi₂O₆ (M=Zn, Mg) Ceramics

With the development of the mobile communications and satellite communications, more and more people focus on the applications of microwave dielectric ceramics in resonators, filters, waveguides and so on, which makes a higher demand for microwave dielectric ceramics. Mixing two or more different material and doping has become an important way to improve the properties of microwave dielectric ceramics.In this paper, MNb2O6-ZrTi2O6 (M=Zn, Mg) ceramics was prepared by solid phase sintering route. The influence of doping CuO and CaF2 on the microwave dielectric properties of MNb2O6-ZrTi2O6 (M=Zn, Mg) ceramics was investigated. The phase structure and microstructure were characterized by X-ray diffraction and scanning electron microscope. The dielectric properties of specimens were measured by parallel-plate resonator method.The result shows:when 0.24ZnNb2O6-0.76ZrTi2O6 ceramics specimens fired in air at 1220-1280℃were doped by CuO or CaF2, with increasing CuO content relative permittivity increased, Q*f value first increased and then decreased, the temperature coefficient of resonant frequency decreased; with increasing CaF2 content, relative permittivity increased and Q*f value decreased.1.0 wt% CuO-doped 0.24ZnNb2O6-0.76ZrTi2O6 ceramics specimens fired in the air at 1240℃have good dielectric properties:relative dielectric constantεr=43.0; Q*f=14630 GHz, the temperature coefficient of resonant frequencyτf= 8 ppm/℃.0.25 wt% CaF2 doped 0.27MgNb2O6-0.73ZrTi2O6 ceramics specimens fired in air at 1425℃have relatively poor dielectric properties:εr= 29.5; Q*f=7538 GHz,τf=28 ppm/℃.