Microwave dielectric properties of BaO–2(1 − x)ZnO–xNd2O3–4TiO2 (x = 0–1.0) ceramics

Microwave dielectric properties of (1 − x)BaZn2Ti4O11–xBaNd2Ti4O12 (x = 0–1.0) ceramics were investigated by the solid-state reaction with the purpose of finding a microwave ceramics with high dielectric constant (ɛr), high quality factor (Q × f) and low temperature coefficient of resonant frequency (τf). A two phase system BaZn2Ti4O11–BaNd2Ti4O12 was formed and SEM photographs show equiaxed BaZn2Ti4O11 grains and columnar BaNd2Ti4O12 grains. The microwave dielectric properties were strongly determined by the chemical composition. As increasing x from 0 to 1.0, the phase composition varied from pure BaZn2Ti4O11, to the two phase system BaZn2Ti4O11–BaNd2Ti4O12 and then to pure BaNd2Ti4O12. Therefore, the ɛr raised from 29.1 to 82.0 and the Q × f values decreased from 54,630 GHz to 8110 GHz, and the τf values increased from −29 ppm/°C to 94 ppm/°C. 0.8BaZn2Ti4O11–0.2BaNd2Ti4O12 ceramics sintered at 1250 °C for 2.5 h had ɛr = 39.1, Q × f = 37,850 GHz and τf = −9 ppm/ °C.