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<p>Layered Aurivillius-type ceramics with the nominal chemical composition Bi₄₋ₓDyₓTi₂FeO₁₂ (x = 0.30, 0.60, 0.90), designated as Dy-BTFO, were prepared successfully by using the conventional solid-state reaction route. The impact of Dy³⁺ substitution on the structural, microstructural, optical, magnetoelectric, dielectric, and impedance properties was studied systematically. X-ray diffraction (XRD) analysis supplemented by Rietveld refinement corroborated development of a single-phase orthorhombic structure of the B2cb space group, with the unit cell volume diminishing progressively as a result of anisotropic lattice distortions brought about by inclusion of Dy. Microstructural characterization indicated evident evolution from plate-like layered grain morphology to rounder grain morphology with higher Dy content, accompanied by greater porosity. Raman spectroscopy exhibited ten active phonon modes with evident red-shift towards lower wavenumber upon doping with Dy addition, indicating lattice softening. Ancillary FTIR spectroscopy determined characteristic vibrational bands of Aurivillius-type structure. The electrical characterization through polarization-electric field (P–E) loops revealed unsaturated behavior at room temperature, while magnetization-field (M–H) loops demonstrated weak ferromagnetic ordering, confirming the coexistence of ferroelectric and magnetic properties, characteristic of multiferroic materials. Notably, x = 0.60 sample presented an enhanced magnetoelectric coupling coefficient (MECC) value of approximately 9.34 mV/(cm·Oe), reflecting its superior magnetoelectric effect. Temperature-dependent dielectric studies revealed paraelectric-to-ferroelectric phase transition (T<sub>C</sub>), which was systematically shifted towards room temperature with the rise in Dy content, reflecting increased tunability for practical applications. Impedance spectroscopy and modulus analysis revealed clear contributions of grain and grain boundary regions, along with the occurrence of non-Debye-type relaxation behavior associated with increased internal resistance. These findings collectively bring to the forefront the potential of Dy-BTFO ceramics as very good material candidates for next-generation multifunctional devices, particularly in magnetoelectric sensors, energy storage, and smart electronics.</p>

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Structural, Microstructural, Magnetoelectric Property Correlation with Complex Impedance Spectroscopy in Dy-Doped Bi4Ti2FeO12 Aurivillius Ceramics

  • 期刊论文

  • 发表日期：

    2025年11月6日

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  • Ramakrishna Masabattula,
  • Deva Sucharitha Chakram,
  • Santosh Nandi,
  • Abdullah Yahya Abdullah Alzahrani,
  • Sana Ben Moussa,
  • Raneesh Balakrishnan,
  • Madhavaprasad Dasari

摘要

Layered Aurivillius-type ceramics with the nominal chemical composition Bi₄₋ₓDyₓTi₂FeO₁₂ (x = 0.30, 0.60, 0.90), designated as Dy-BTFO, were prepared successfully by using the conventional solid-state reaction route. The impact of Dy³⁺ substitution on the structural, microstructural, optical, magnetoelectric, dielectric, and impedance properties was studied systematically. X-ray diffraction (XRD) analysis supplemented by Rietveld refinement corroborated development of a single-phase orthorhombic structure of the B2cb space group, with the unit cell volume diminishing progressively as a result of anisotropic lattice distortions brought about by inclusion of Dy. Microstructural characterization indicated evident evolution from plate-like layered grain morphology to rounder grain morphology with higher Dy content, accompanied by greater porosity. Raman spectroscopy exhibited ten active phonon modes with evident red-shift towards lower wavenumber upon doping with Dy addition, indicating lattice softening. Ancillary FTIR spectroscopy determined characteristic vibrational bands of Aurivillius-type structure. The electrical characterization through polarization-electric field (P–E) loops revealed unsaturated behavior at room temperature, while magnetization-field (M–H) loops demonstrated weak ferromagnetic ordering, confirming the coexistence of ferroelectric and magnetic properties, characteristic of multiferroic materials. Notably, x = 0.60 sample presented an enhanced magnetoelectric coupling coefficient (MECC) value of approximately 9.34 mV/(cm·Oe), reflecting its superior magnetoelectric effect. Temperature-dependent dielectric studies revealed paraelectric-to-ferroelectric phase transition (TC), which was systematically shifted towards room temperature with the rise in Dy content, reflecting increased tunability for practical applications. Impedance spectroscopy and modulus analysis revealed clear contributions of grain and grain boundary regions, along with the occurrence of non-Debye-type relaxation behavior associated with increased internal resistance. These findings collectively bring to the forefront the potential of Dy-BTFO ceramics as very good material candidates for next-generation multifunctional devices, particularly in magnetoelectric sensors, energy storage, and smart electronics.