Effects of zinc substitution on the dielectric properties of Ca5Nb4TiO17 microwave ceramics

Ca5-xZnxNb4TiO17 ceramics with 0 <= x <= 0.4 were prepared through a solid-state reaction method. Effects of zinc substitution on sintering behavior and microwave dielectric properties of Ca5Nb4TiO17 ceramics were investigated. The sintering temperature was significantly lowered from 1480 degrees C for pure Ca5Nb4TiO17 to 1260 degrees C for x = 0.4. The microwave dielectric properties are strongly correlated with the composition. It is worth noting that the temperature coefficient of resonant frequency (T-f) displays a tendency toward positive value, ranging from -126.4 ppm/degrees C to -8.6 ppm/degrees C. A temperature stable microwave ceramic with dielectric constant of 52 and Q x f value of 9937 GHz is achieved at x = 0.4 and is a potential candidate for application as cores in dielectrically loaded antennas.