Microstructure and microwave dielectric properties of Ba6-3xSm8+2xTi18O54 ceramics with various BaxSr1-xTiO3 additions

The Ba_6?3xSm_8+2xTi₁₈O₅₄ (x=2/3) microwave dielectric ceramics were prepared by traditional solid sate reaction technique. The experiment was based on the Ba_6?3xSm_8+2xTi₁₈O₅₄ (BST) microwave dielectric ceramics doped with a certain amount of Bi₂O₃, then the effects of Ba_xSr_1?xTiO₃ additives on the structure and microwave dielectric properties of Ba_6?3xSm_8+2xTi₁₈O₅₄ ceramics were investigated using X-ray diffraction and scanning electron microscopy. In this study, the small amount substitution of Sr for Ba was effective for the microwave dielectric properties of BST, especially the τ_f could be tuned to near zero. The result showed that the BST possessed excellent dielectric properties when the addition of Bi₂O₃ and Ba_xSr_1?xTiO₃ was 1 wt.% respectively: ?_r=79.6, Q·f=10789 GHz, τ_f=?1.5 ppm/°C.