Low temperature sintering and dielectric properties of (Zr_0.8Sn_0.2)TiO₄ microwave ceramics using La₂O₃/BaO additives

The effects of La₂O₃/BaO additives on the sintering behavior and dielectric properties of (Zr_0.8Sn_0.2)TiO₄ (ZST) microwave ceramics were investigated. With La₂O₃/BaO additives, the sintering temperatures can be effectively lowered. The dielectric properties of ZST ceramics were strongly dependent on the amount of La₂O₃/BaO additives. As the amount of La₂O₃/BaO additives increased from 0.5 to 2.0 wt.%, the dielectric constants ε_r increased following the trend with density and the τ_f values of dense sintered ZST ceramics increased from +1.3 to +18.3 ppm°C^-1 steadily. The quality values Q first increased, reached a maximum at 1.0 wt.% La₂O₃/BaO, and then decreased with the further increase of La₂O₃/BaO amount for all sintering temperatures. The 1.0 wt.% La₂O₃/BaO-doped ZST ceramics sintered at 1350°C for 4 h had the optimum dielectric properties: ε_r = 38; τ_f = +5.6 ppm°C^-1; Q = 11575 (1.8 GHz). At the level of 0.5-2.0 wt.% additives, no second phase was observed by the X-ray diffraction (XRD) analysis.