Barium strontium titanate is one of the most popular tunable material in microwave technologies. Perovskite BST is a material with a high dielectric constant value which strongly depends on its purity, grain size, method of preparation and crystallographic phase. BST consists of a solid solution of barium titanate which is a ferroelectric material with a Curie temperature of 120°C and strontium titanate with a Curie temperature of -168°C. As the strontium content in BST increases, the Curie temperature of the material decreases which allows to obtain the material working in a specific temperature range by selecting the appropriate stoichiometry. Barium strontium titanate is one of the ferroelectric materials that has many advantages, such as high dielectric constant, low loss, high tunability, low value of dielectric loss, high mechanical strength and good thermal stability.
The aim of this work was optimization of the synthesis of BST and preparation of ferroelectric ceramic-polymer composites based on BST and different types of polymers. The first stage of the research was the synthesis of barium strontium titanate by the solid state reaction between barium and strontium carbonates and titanium oxide and the characterization of synthesized powders. The BST/polymer composites were obtained by tape casting. Then the influence of the compositions of the suspensions on their rheological properties was examined as well as on the physicochemical and electrical properties of the obtained composite materials.
Ferroelectric ceramic-polymer composites based on BST are characterized by low values of dielectric losses, the possibility of changing the relative value of electric permittivity in the external electric field and flexibility. These composites can be used in tunable antenna systems, satellite telecommunications, materials imaging and chemical analysis.
Acknowledgements: This work was financially supported by the Polish National Science Centre, project No 2018/30/Q/ST8/00205.