Structure and dielectric properties of Ba1−xSrxCuSi2O6-Ba0.55Sr0.45TiO3 ferroelectric-dielectric composite ceramics

yBa1−xSrxCuSi2O6-(1−y) Ba0.55Sr0.45TiO3 (x = 0, 0.2 and y = 10 wt%, 30 wt%) ferroelectric-dielectric composite ceramics were prepared by the solid-state sintering method. The relationship among phase composition, microstructures and dielectric properties has been investigated. By adjusting the content of the Ba1−xSrxCuSi2O6 and the content of Sr2+ in the Ba1−xSrxCuSi2O6, the effect of the dielectric material on BST was studied. With the increase of Ba1−xSrxCuSi2O6 content and the increase of the Sr2+ content, the dielectric peak of the composite material is gradually suppressed and broadened, and the Curie temperature (Tc) moves to the low temperature. The introduction of Ba1−xSrxCuSi2O6 reduced the permittivity of the composite material to a certain extent, at the same time, the dielectric tunability and quality factor (Q) value are maintained at a high level. The dielectric tunability of the four composite ceramics obtained is still higher than 10% under the applied electric field (at 30 kV/cm). The 30 wt% BCSO–70 wt% BST55 system and the 30 wt% BSCSO–70 wt% BST55 system has lower dielectric permittivity (830, 577), higher dielectric tunability (17.3%, 10.2% at 30 kV/cm) and a decent Q value (149 at 1.25 GHz, 168 at 1.31 GHz).