Adjustable microwave dielectric properties of ZnO–TiO 2 –ZrO 2 –Nb 2 O 5 composite ceramics via controlling the raw ZrO 2 content and sintering temperature

A series of 2.5ZnO–(5−x)TiO2–xZrO2–2.5Nb2O5 (abbreviated as ZTZN, 0.2 ≤ x ≤ 0.4) composite ceramics were prepared by a solid state reaction method. The phase composition and microwave dielectric properties of the ceramics were investigated. X-ray diffraction patterns displayed the coexistence of ZnTiNb2O8 and Zn0.17Nb0.33Ti0.5O2 phases. With increasing the sintering temperature, the bulk density (ρ), permittivity (e r ) and temperature coefficient of resonator frequency (τ f ) increased. With increasing the ZrO2 content, the ρ firstly increased and then decreased, Q × f value increased, e r and τ f value decreased. Importantly, the τ f value of ZTZN ceramics (0.2 ≤ x ≤ 0.4) could be adjusted to near-zero. The 2.5ZnO–4.7TiO2–0.3ZrO2–2.5Nb2O5 ceramics sintered at 1075 °C exhibited the best comprehensive performances of Q × f = 30,155 GHz, e r = 44 and τ f = 0.89 ppm/°C, indicating that they are candidates for microwave devices.