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<p>This study focuses on the crystal structure and magnetic properties of Ba–Mn co-substituted BiFeO<sub>3</sub> ceramics with nominal composition Bi<sub>0.85</sub>Ba<sub>0.15</sub>Fe<sub>1−<i>x</i></sub>Mn<sub><i>x</i></sub>O<sub>3</sub> (0.1 ≤ <i>x</i> ≤ 0.5), synthesized via solid-state reaction. X-ray diffraction and piezoresponse force microscopy confirm a composition-driven structural transition from a polar rhombohedral (<i>R</i>3<i>c</i>) phase to a centrosymmetric tetragonal (<i>I</i>4/<i>mcm</i>) phase occurring at <i>x</i>&#xa0;≈&#xa0;0.4. Mössbauer spectroscopy and scanning electron microscopy reveal that the weak ferromagnetic behavior observed at room temperature is governed by trace amounts of Mn-doped BaFe<sub>12</sub>O<sub>19</sub> impurity phase – undetectable by conventional XRD. While low-temperature magnetization enhancement in Mn-rich samples likely arises from Mn<sup>3+</sup>–O–Mn<sup>4+</sup> ferromagnetic interactions, these results underscore the difficulty of isolating intrinsic magnetic responses in Ba-substituted BiFeO<sub>3</sub>. Our findings emphasize the necessity of cross-validating structural and magnetic measurements to avoid misinterpretation of multiferroic behavior in systems prone to impurity formation.</p>

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Structural evolution and magnetic behavior of Ba- and Mn-substituted BiFeO3: impurity-driven artifacts and intrinsic limitations

  • 期刊论文

  • 发表日期：

    2025年11月22日

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  • M. Das,
  • B. F. O. Costa,
  • J. A. Paixão,
  • V. A. Khomchenko

摘要

This study focuses on the crystal structure and magnetic properties of Ba–Mn co-substituted BiFeO3 ceramics with nominal composition Bi0.85Ba0.15Fe1−xMnxO3 (0.1 ≤ x ≤ 0.5), synthesized via solid-state reaction. X-ray diffraction and piezoresponse force microscopy confirm a composition-driven structural transition from a polar rhombohedral (R3c) phase to a centrosymmetric tetragonal (I4/mcm) phase occurring at x ≈ 0.4. Mössbauer spectroscopy and scanning electron microscopy reveal that the weak ferromagnetic behavior observed at room temperature is governed by trace amounts of Mn-doped BaFe12O19 impurity phase – undetectable by conventional XRD. While low-temperature magnetization enhancement in Mn-rich samples likely arises from Mn3+–O–Mn4+ ferromagnetic interactions, these results underscore the difficulty of isolating intrinsic magnetic responses in Ba-substituted BiFeO3. Our findings emphasize the necessity of cross-validating structural and magnetic measurements to avoid misinterpretation of multiferroic behavior in systems prone to impurity formation.