We report the fabrication of novel multiferroic nanostructured bismuth ferrite (BiFeO_3) fibers using the sol-gel based electrospinning technique. Phase pure BiFeO_3 fibers were prepared by thermally annealing the electrospun BiFeO_3/polyvinylpyrrolidone composite fibers in air for 1h at 600 °C. The x-ray diffraction pattern of the fibers (BiFeO_3) obtained showed that their crystalline structures were rhombohedral perovskite structures. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed that the BiFeO _3 fibers were composed of fine grained microstructures. The grains were self-assembled and self-organized to yield dense and continuous fibrous structures. The magnetic hysteresis loops of these nanostructured fibers displayed the expected ferromagnetic behavior, whereby a coercivity of ～ 250Oe and a saturation magnetization of ～ 1.34emug~(-1) were obtained. The ferroelectricity and ferroelectric domain structures of the fibers were confirmed using piezoresponse force microscopy (PFM). The piezoelectric hysteresis loops and polar domain switching behavior of the fibers were examined. Such multiferroic fibers are significant for electroactive applications and nano-scale devices.
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