2016/05/05 by Mohapatra, S. R., Sahu, B., Chandrasekhar, M. +4
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.1605.01570
Structural, impedance, ferroelectric and magnetic properties were examined in multiferroic Bi2Fe4(1-x)Co4xO9 (0≤x≤0.02) ceramics synthesized via solid-state reaction method. X-ray diffraction analysis and Rietveld refinement showed secondary phase formation (for x≥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 (2Pr) from 0.1193 μC/cm2 (x=0) to 0.2776 μC/cm2 (x=0.02). Besides, room temperature M-H measurement showed improved ferromagnetic hysteresis loop for all the modified samples. The remnant magnetization (Mr) and coercive field (Hc) 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 Co3+ ions leading to breakdown of balance between the anti-parallel sub lattice magnetization of Fe3+ ions.