Phase constitution, microstructures and microwave dielectric properties of CaxZn1−xZr0.8Sn0.2Nb2O8 ceramics

The phase constitution, microstructures and microwave dielectric properties of CaxZn1−xZr0.8Sn0.2Nb2O8 (x = 0.00, 0.05, 0.10, 0.15) ceramics prepared via a solid-state reaction method were reported for the first time. The X-ray diffraction patterns of CaxZn1−xZr0.8Sn0.2Nb2O8 ceramics showed the monoclinic structure of ZnZrNb2O8 and the second phase columbite CaNb2O6 were obtained. The microwave dielectric properties of the CaxZn1−xZr0.8Sn0.2Nb2O8 ceramics were strongly affected by the change of crystal structure and the content of second phase. With the increasing Ca2+ content, the dielectric constant (e r ) and the Qf value decreased and the temperature coefficient of resonant frequency (τ f ) moved to the positive direction. The typical values of e r = 26.64, Qf = 61,350 GHz, τ f = −21.43 × 10−6/°C were obtained for CaxZn1−xZr0.8Sn0.2Nb2O8 (x = 0.15) specimens sintered at 1275 °C for 6 h.