Layered SrTiO3/BaTiO3 composites with significantly enhanced dielectric permittivity and low loss

Ferroelectric ceramic materials are receiving increasing attention due to their extensive applications in electrical systems. In this work, three-layer BaTiO3/SrTiO3 ceramic composites consisting of one Ba1-xTiO3-SrxTiO3 (at x = 5, 10, 20 and 30) composite interlayer sandwiched by two BaTiO3 outer layers were fabricated. And the effects of SrTiO3 modification on their phase structures, microstructures and dielectric performance were studied in detail. A pure perovskite phase was observed in the Ba1-xTiO3-SrxTiO3 ceramic composites. The BaTiO3 ceramic doping by SrTiO3 exhibited refined grain size. With increased SrTiO3 content, both the permittivity and dielectric loss have increased. Furthermore, a layered structure was designed to enhance the dielectric properties. Consequently, a high permittivity of 7118 and low loss of 0.028 were achieved at 10 kHz in BaTiO3-30 w% SrTiO3–BaTiO3 three-layer ceramic composites. In summary, the introduction of SrTiO3 is believed to reduce the BaTiO3 Curie temperature and greatly improve its permittivity at room temperature. Furthermore, the accumulation of charge carriers at the interface significantly increases the permittivity, while preventing the transport of the charge carriers and reducing the loss. The ultrahigh permittivity and low loss make these composites promising candidates for microwave antennas, field effect transistors and dielectric capacitors.