Journal of Advanced Ceramics


solid-state reaction, (1-x)CoTiNb2O8-xZnNb2O6 ceramics, crystal structure, microwave dielectric property


(1-x)CoTiNb2O8-xZnNb2O6 microwave dielectric ceramics were prepared via the conventional solid-state reaction route with the aim of reducing the τf value and improving the thermal stability. The phase composition and the microstructure were investigated using X-ray diffraction, Raman spectra, and scanning electron microscopy. A set of phase transitions which were induced by composition had been confirmed via the sequence: rutile structure→coexistence of rutile and columbite phase→columbite phase. For (1-x)CoTiNb2O8-xZnNb2O6 microwave dielectric ceramics, the addition of ZnNb2O6 content (x = 0-1) led to the decrease of εr from 62.98 to 23.94. As a result of the high Q × ƒ of ZnNb2O6 ceramics, the increase of ZnNb2O6 content also led to the lower sintering temperatures and the higher Q × ƒ values. The τf value was reduced from +108.04 (x = 0) to - 49.31 ppm/℃ (x = 1). Among them, high density 0.5CoTiNb2O8-0.5ZnNb2O6 ceramics were obtained at 1175 ℃ with excellent microwave dielectric properties of εr 39.2, Q × ƒ 40013 GHz, and τf + 3.57 ppm/℃.


Tsinghua University Press