Effect of Sm₂O₃/ZnO on the microstructure and microwave dielectric properties of (Zr_0.8,Sn_0.2)TiO₄ ceramics

(Zr_0.8, Sn_0.2)TiO₄ ceramics containing ZnO and Sm₂O₃ as sintering aids are prepared by the conventional solid-state reaction. The effects of sintering parameters such as sintering temperature, sintering time and increasing Sm₂O₃ concentration on structural and dielectric properties are investigated. A secondary phase is not observed for the levels of 0.5-1.5 wt% Sm₂O₃ additions. Crystallite size of the sintered ZST ceramics ranges between 20 and 55 nm. The dielectric constant (ε_r) and temperature coefficient of the resonance frequency (τ_f) are not significantly affected. The unloaded quality factors (Q) are effectively promoted by Sm₂O₃ additions. A ε_r value of 39.3 and Qxf_o of 63,850 (at 11.94 GHz) have been obtained for 1 wt% ZnO added (Zr_0.8,Sn_0.2)TiO₄ ceramics with 1 wt% Sm₂O₃. The increase in Qxf_o is attributed to the increase in grain size. The effect of grain size on the microwave dielectric properties of ZST is discussed. (author)