Tunable ceramic-polymer composites for electronic applications

Emilia Pietrzak, Emilia Pawlikowska, Konrad Godziszewski, Yevhen Yashchyshyn, Mikołaj Szafran

Quarterly No. 1, 2015 pages 54-57

DOI:

keywords: tunability, ceramic-polymer composites, BST (barium strontium titanate), tape casting

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abstract The ceramic-polymer composites presented in the paper have unusual properties. These materials can operate in a wide range of electromagnetic spectrum and consequently they can be potentially used in imaging techniques, chemical characterization, security systems, quality control and very high data rate communication systems. Microwave applications are widely understood as antennas and radiocommunication devices. Materials used to produce equipment operating at high frequencies, even subterahertz, must be subjected to restrictive verification. The most commonly used materials in radio technology are ferroelectrics. They are characterized by a high value of dielectric permeability. A typical example of ferroelectric material used and widely known is barium strontium titanate (abbr. BST), which is applied in microwave technology. Barium strontium titanate was prepared using solid-state synthesis process. The materials used in the fabrication were ceramic powders: BaCO₃, SrCO3 and TiO₂. Thanks to the combination of an elastic polymer and ceramic powder with ferroelectric properties, it is possible to use such a material in devices operating at a very high frequency. The commercial materials used in the research allow one to produce composites by the tape casting method and obtain antennas. Ferroelectric ceramic-polymer tapes based on doped and undoped ceramic powder with different BST stoichiometrics have been prepared. The tunability of samples prepared of pure and doped Ba_0.65Sr_0.35TiO₃, Ba_0.58Sr_0.42TiO₃ and Ba_0.51Sr_0.49TiO₃ was measured. The relationship between the stoichiometry, or doped and undoped powder has been also found. It was observed that a higher ratio of Ba to Sr caused an increase in tunability values. Moreover, the addition of Ni₂O₃ to ceramic powder positively effected the tunability parameter.