Abstract
ZnNb(2)O(6)-based microwave dielectric ceramics have attracted considerable attention due to their high quality factor (Q × f) and low sintering temperature, but their application was limited by poor temperature stability with a large negative temperature coefficient of resonant frequency (τ(f)). Herein, novel (1 - x)ZnNb(2)O(6-x)Ca(0.5)Sr(0.5)TiO(3) (x = 0.05-0.125) composite ceramics were designed and fabricated. The used ZnNb(2)O(6) and Ca(0.5)Sr(0.5)TiO(3) were synthesized through solid-phase reaction by using stoichiometric metal oxides or carbonates as the raw materials at 650 and 1100 °C, respectively. The composite ceramics were prepared by solid-state sintering, and the sintering parameters were optimized at 1175 °C for 4 h by visual high-temperature deformation analysis. A focus was paid on the temperature stability and compositional effects of Ca(0.5)Sr(0.5)TiO(3) of the obtained composited ceramics. As the Ca(0.5)Sr(0.5)TiO(3) content increases, the dielectric constant (ε(r)) and Q × f gradually decrease, while τ(f) shifts toward positive values. At x = 0.075, the composite ceramics sintered at 1175 °C for 4 h exhibit near-zero τ(f) (-8.99 ppm/°C), coupled with ε(r) = 23.23 and Q × f = 21,686 GHz. This study provides theoretical guide and material support for designing and fabricating various high-performance thermally stable microwave dielectric ceramics for 5G communication devices and future communication technologies.