Microstructure and microwave dielectric behavior of 0.6ZrO₂–0.4(Zn_1/3Nb_2/3)O₂–xSnO₂–yTiO₂ ceramics

0.6ZrO₂–0.4(Zn_1/3Nb_2/3)O₂–xSnO₂–yTiO₂ ceramics were prepared by the conventional solid state reaction method. The microstructure and microwave dielectric properties have been investigated as functions of the Sn content and sintering temperature. Scanning electron microscopy analysis demonstrated that dense ceramics were obtained. In the ceramics with x = 0.1 and 0.2, grain growth is the discontinuous-type. As x increases, the discontinuous-type of grain growth is suppressed. However, the average grain size increases. The microwave dielectric properties, especially the quality factor and temperature coefficient of resonance frequency value, were sensitive to the content of Sn. As the content of Sn increased from 0.10 to 0.40, the dielectric constant of the 0.6ZrO₂–0.4(Zn_1/3Nb_2/3)O₂–xSnO₂–yTiO₂ ceramics decreased gradually from 39.5 to 31.5, the Q × f value increased from 40,000 to 47,500 GHz, and τ _f value shifted slightly from +4.8 to −39.1 ppm/°C. The 0.6ZrO₂–0.4(Zn_1/3Nb_2/3)O₂–0.2SnO₂–0.8TiO₂ ceramics sintered at 1220 °C exhibited relatively ideal dielectric properties with a dielectric constant of 36.59, Q × f value of 43,200 GHz, and temperature coefficient of resonant frequency of −5.9 ppm/ °C.