Effects of ZBS glass addition on sintering behavior and properties of Ba_6−3x(Sm_1−yBi_y)_8+2xTi₁₈O₅₄(x = 2/3, y = 0.1) microwave dielectric ceramics

The ZnO-B₂O₃-SiO₂(ZBS)-doped Ba_6−3x(Sm_1−yBi_y)_8+2xTi₁₈O₅₄ (x = 2/3, y = 0.1, BST) microwave dielectric ceramics were prepared via solid-state reaction route. The sintering behavior, microstructure and microwave dielectric properties of the ceramics were investigated systematically. The main crystalline phase of the ceramics was orthorhombic tungsten-bronze structure. But more than 3 wt% ZBS content leaded to secondary phase which were Bi_0.56Sm_1.44Ti₂O₇ and BaTi₇O₁₄. The results illustrated that large addition of ZBS would have an effect on the formation of the pure phase of BST(x = 2/3, y = 0.1) ceramics. The addition of ZBS as liquid phase sintering aid lowered the sintering temperature of BST ceramics successfully from 1250 to 1050 °C. However, excessive ZBS doping deteriorated the dielectric properties of ceramics dramatically. Considering the sintering temperature and microwave dielectric properties of the samples, the BST ceramics with 3 wt% ZBS doping content sintered at 1100 °C had the good dielectric properties: ε_r = 68.4133, Q × f = 1879.89 GHz, τ_f = − 18.57 ppm/ °C.