Frequency agile BST materials for microwave applications

(Ba1-xSrx)TiO3 solid solution (BST), with different molar compositions (x = 0.25, 0.5, 0.75, 0.9) Were prepared by conventional solid-state reaction from raw materials. Structural parameters, crystallite sizes and bulk densities were determined. Perovskite type polycrystalline structure of the BST ceramics was revealed by X-ray diffraction (XRD) data. The dependence of permittivity and losses at low frequency (1 kHz) was analyzed. The microwave investigations at room temperature revealed dielectric constant around 1000 and loss smaller than 1% at 1.1 GHz. The results indicate that some BST dielectric ceramics are suitable in paraelectric phase for microwave devices. The dielectric constant can be adjusted by using a DC-bias field and such materials are appropriate for manufacturing electric field controlled components such as resonators, phase shifters etc.