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The multiferroic magnetoelectric composites have attracted great interest due to some new expected physics and wide practical applications. However, the low resistivity restricts their further applications. In this work, multiferroic 0.8BaTiO3-0.2BaFe12- xMn xO19 composite ceramics were prepared by microwave-hydrothermal and microwave-sintering methods. It was found that the dielectric constant of the composites increased with increasing x, while the resistivity increased gradually. Accordingly, the dielectric loss dropped as expected and the P-E loops showed slimmer shapes after introducing of Mn ions. In addition, the magnetic hysteresis loops of the composite ceramics prepared showed an excellent ferromagnetic behavior. In summary, smaller leakage current and slim P-E loops were obtained through Mn ion doping in BaFe12O19 and forming BaTiO3-BaFe12− xMn xO19 composite ceramics while maintaining their good ferromagnetic property successfully. [ABSTRACT FROM AUTHOR]

Multiferroic (1− x)Bi2Fe4O9− xBaFe12O19 ( x = 0.07, 0.08, 0.10, 0.12, 0.15, 0.20) composites were prepared using microwave hydrothermal and microwave sintering methods. X-ray diffraction analysis of the composites revealed the formation of di-phase compounds with barium hexaferrite and mullite bismuth ferrite, respectively. SEM (scanning electron microscope) measurements on the sintered surfaces of the composites displayed the micro-sized of Bi2Fe4O9 matrix and nano-sized BaFe12O19. The study of Dielectric and complex impedance exhibited the presence of grain and grain boundary effects, and a negative temperature coefficient of resistance in the materials. The ferroelectric hysteresis loops showed an obvious ferroelectric behavior. The Mr was up to 19.09 emu g−1 (much larger than pure Bi2Fe4O9 matrix), indicating that increasing BaFe12O19 content could enhance the ferromagnetic properties. The value of Mr/ Ms for all the samples was higher than 0.5 (especially, the maximum was up to 0.89) and it is preferred in many applications such as magnetic recording media of high density and permanent magnets. [ABSTRACT FROM AUTHOR]

Ba 0.4 Sr 0.6 TiO 3 (BST) powders were prepared by hydrothermal method, the ceramics were sintered in N 2 , air and O 2 atmosphere respectively. The effect of sintering atmosphere on the microstructure, dielectric properties, and energy storage performance of BST ceramics were investigated. The grain size of the BST ceramics sintered in O 2 atmosphere was reduced to 0.44 µm, indicating the grain growth was significantly inhibited with increasing oxygen partial pressure due to the lack of oxygen vacancy. Dielectric relaxation behavior was observed in the BST ceramics, and the degree of which was increased with increasing oxygen partial pressure. BST ceramics sintered in O 2 atmosphere showed the largest critical breakdown strength of 16.72 kV/mm, at which the highest energy storage density of 1.081 J/cm 3 and a moderate energy storage efficiency of (73.78%) were obtained. The dependence of energy-storage properties on applied field was also investigated, it was found that the energy storage density increased with increasing applied filed while the energy storage efficiency decreased with increasing applied filed. [ABSTRACT FROM AUTHOR]