The effects of La2O3/BaO additives on the sintering behavior and dielectric properties of (Zr0.8Sn0.2)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 epsilon(r) increased following the trend with density and the tau(f) values of dense sintered ZST ceramics increased from +1.3 to +18.3 ppmdegreesC(-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 1350degreesC for 4h had the optimum dielectric properties: epsilon(r) = 38; tau(f) = +5.6 ppmdegreesC(-1); Q = 11 575 (1.8GHz). At the level of 0.5-2.0 wt.% additives, no second phase was observed by the X-ray diffraction (XRD) analysis. (C) 2002 Elsevier Science B.V. All rights reserved.