Magnetoelectric coupling and phase transition in BiFeO3 and (BiFeO3)0.95(BaTiO3)0.05 ceramics
Tu, C. -S.
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In situ high-resolution synchrotron x-ray diffraction reveals a local minimum in rhombohedral distortion angle α R (associated with an inflection in the lattice constantaR ) near 400 and 350 °C in BiFeO3 (BFO) and (BiFeO3)0.95(BaTiO3)0.05 (BFO–5%BT), respectively. It suggests a coupling between ferroelectric and magnetic parameters near the antiferromagnetic–paramagnetic transition, which is responsible for the broad frequency-dependent dielectric maxima. A rhombohedral (R)–orthorhombic (O)–cubic (C) transition sequence takes place near 820 and 850 °C in BFO upon heating. BFO–5%BT exhibits a R–C transition near 830 °C. The BaTiO3 substitution can enhance dielectric and ferromagnetic responses and reduce electric leakage. The dielectric loss of BFO–5%BT remains less than 0.04 below 150 °C.
T.-H. Wang, C.-S. Tu, H.-Y. Chen, Y. Ding, T.C. Lin, Y.-D. Yao, V.H. Schmidt, and K.-T. Wu, “Magnetoelectric coupling and phase transition in BiFeO3 and (BiFeO3)0.95(BaTiO3)0.05 ceramics,” Journal of Applied Physics 109, 044101 (2011).