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

The Ba6−3xSm8+2xTi18O54 (x=2/3) microwave dielectric ceramics were prepared by traditional solid sate reaction technique. The experiment was based on the Ba6−3xSm8+2xTi18O54 (BST) microwave dielectric ceramics doped with a certain amount of Bi2O3, then the effects of BaxSr1−xTiO3 additives on the structure and microwave dielectric properties of Ba6−3xSm8+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 τf could be tuned to near zero. The result showed that the BST possessed excellent dielectric properties when the addition of Bi2O3 and BaxSr1−xTiO3 was 1 wt.% respectively: ɛr=79.6, Q·f=10789 GHz, τf=−1.5 ppm/°C.