Tetragonal tungsten bronze/barium hexaferrite room-temperature multiferroic composite ceramics

Abstract

The spontaneously formed multiferroic composite based on tetragonal tungsten bronze structure was successfully synthesized in the form of ceramics by the solid-state reaction. The crystallization of the ceramics in the tetragonal tungsten bronze structure Ba2SmFeNb4O15 and the presence of a secondary magnetic phase of barium hexaferrite BaFe12O19 were established by structural investigation. The hysteresis behavior describing the polarization as a function of an applied electric field and the high ferroelectric Curie temperature ≈ 417 K evidenced the room-temperature ferroelectric properties of the synthesized material. While the piezoelectric coefficients were determined to be around 1.3 pm/V, the microscopic polar domains of the composite ceramics were established by microelectromechanical study. The hysteresis loop of the magnetization versus magnetic field and the high magnetic transition temperature ≈ 590 K evidenced the ferromagnetic properties of the secondary phase and its presence at room temperature. Moreover, the spatial distribution of the magnetic domains was determined microscopically. In this study, not only the multiferroic properties of the Ba2SmFeNb4O15/BaFe12O19 composites have been studied and presented, but the distribution of the polar and magnetic properties was locally investigated as well.