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arXiv · 1605.01570

Effect of cobalt substitution on structural, impedance, ferroelectric and magnetic properties of multiferroic Bi_2Fe_4O_9 ceramics

S. R. Mohapatra·B. Sahu·M. Chandrasekhar·P. Kumar·S. D. Kaushik·S. Rath·A. K. Singh
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Abstract

Structural, impedance, ferroelectric and magnetic properties were examined in multiferroic Bi_{2}Fe_{4(1-x)}Co_{4x}O_{9} (0$\leq$x$\leq$0.02) ceramics synthesized via solid-state reaction method. X-ray diffraction analysis and Rietveld refinement showed secondary phase formation (for x$\geq$0.01) which was subsequently confirmed from room temperature Raman spectroscopy study. The frequency dependence of impedance and electric modulus of the material showed the presence of non-Debye type relaxation in all the samples. The values of the activation energies calculated from imaginary impedance and modulus lie in the range of 0.92-0.99 eV which confirmed that the oxygen vacancies play an important role in the conduction mechanism. Moreover, suitable amount of Co substitution significantly enhanced the remnant polarisation (2P_{r}) from 0.1193 $\mu$C/cm^{2} (x=0) to 0.2776 $\mu$C/cm^{2} (x=0.02). Besides, room temperature M-H measurement showed improved ferromagnetic hysteresis loop for all the modified samples. The remnant magnetization (M_{r}) and coercive field (H_{c}) increased from 0.0007 emu/gm and 42 Oe for x=0 to 0.1401 emu/gm and 296 Oe for x=0.02. The improved ferroelectricity was due to Co 3d-O 2p hybridization and enhanced magnetization originated from the partial substitution of Co^{3+} ions leading to breakdown of balance between the anti-parallel sub lattice magnetization of Fe^{3+} ions.

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S. R. Mohapatra, B. Sahu, M. Chandrasekhar, P. Kumar, S. D. Kaushik, S. Rath, A. K. Singh. 2016-05-05. Effect of cobalt substitution on structural, impedance, ferroelectric and magnetic properties of multiferroic Bi_2Fe_4O_9 ceramics. https://arxiv.org/abs/1605.01570

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