Synthesis, characterization and dielectric properties of a novel temperature stable (1−x)CoTiNb2O8−xZnNb2O6 ceramic

(1− x )CoTiNb 2 O 8 −xZnNb 2 O 6 microwave dielectric ceramics were prepared via the conventional solid-state reaction route with the aim of reducing the τ f 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 )CoTiNb 2 O 8 − x ZnNb 2 O 6 microwave dielectric ceramics, the addition of ZnNb 2 O 6 content ( x = 0–1) led to the decrease of ε r from 62.98 to 23.94. As a result of the high Q × f of ZnNb 2 O 6 ceramics, the increase of ZnNb 2 O 6 content also led to the lower sintering temperatures and the higher Q × f values. The τ f value was reduced from +108.04 ( x = 0) to − 49.31 ppm/°C ( x = 1). Among them, high density 0.5CoTiNb 2 O 8 -0.5ZnNb 2 O 6 ceramics were obtained at 1175 °C with excellent microwave dielectric properties of ε r 39.2, Q × f 40013 GHz, and τ f +3.57 ppm/°C.