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<p>LuFeO<sub>3</sub> (LFO) is a perovskite oxide with promise for optical and electroceramic applications. In the present study, LFO and Co-substituted compositions (LFO, LuFe<sub>0.95</sub>Co<sub>0.05</sub>O<sub>3</sub>, and LuFe<sub>0.90</sub>Co<sub>0.10</sub>O<sub>3</sub>) were synthesized by a conventional solid-state route and characterized by SEM, Raman spectroscopy, diffuse reflectance, and broadband dielectric/impedance measurements. Co substitution alters the powder microstructure, yielding more irregular agglomerates composed of finer sub-units than undoped LFO. Dielectric spectra showed that the loss tangent (tanδ), the dissipation factor, of investigated samples was below 1 over the studied temperature–frequency window. It was seen that Co substitution decreased dielectric loss in the mid-to-high frequency region but raised low-frequency loss at advanced temperatures. The real part of impedance <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\:{Z}^{{\prime\:}}\)</EquationSource> </InlineEquation>declined with both temperature and frequency, and Nyquist plots displayed depressed arcs, indicating non-Debye behavior with distributed grain and grain-boundary contributions. Arrhenius analysis of relaxation maxima yielded activation energies of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\:\sim\:\)</EquationSource> </InlineEquation>0.32–0.76&#xa0;eV, consistent with oxygen-vacancy energies. Raman spectra revealed Co-induced lattice perturbations, including mode broadening/attenuation and red-shifts in the 200–600&#xa0;cm<sup>− 1</sup> range, together with a strengthened stretching feature near 600–650&#xa0;cm<sup>− 1</sup>. Kubelka–Munk analysis was utilized to determine the band gaps of the studied samples, 2.19&#xa0;eV (LFO), 2.29&#xa0;eV (5% Co), and 2.14&#xa0;eV (10% Co). Overall, modest Co substitution provides an effective route to tailor vacancy-mediated relaxation and reduce MHz-range dielectric dissipation in LFO-based functional ceramics.</p>

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Dielectric relaxation and optical band-gap modulation in LuFe1−xCoxO3 powders

  • 期刊论文

  • 发表日期：

    2026年5月11日

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  • R. Carterette,
  • M. Coskun,
  • D. Sobola,
  • Y. Yildirim,
  • C. Sen,
  • Z. Durmus,
  • M. Caglar,
  • O. Polat

摘要

LuFeO3 (LFO) is a perovskite oxide with promise for optical and electroceramic applications. In the present study, LFO and Co-substituted compositions (LFO, LuFe0.95Co0.05O3, and LuFe0.90Co0.10O3) were synthesized by a conventional solid-state route and characterized by SEM, Raman spectroscopy, diffuse reflectance, and broadband dielectric/impedance measurements. Co substitution alters the powder microstructure, yielding more irregular agglomerates composed of finer sub-units than undoped LFO. Dielectric spectra showed that the loss tangent (tanδ), the dissipation factor, of investigated samples was below 1 over the studied temperature–frequency window. It was seen that Co substitution decreased dielectric loss in the mid-to-high frequency region but raised low-frequency loss at advanced temperatures. The real part of impedance \(\:{Z}^{{\prime\:}}\) declined with both temperature and frequency, and Nyquist plots displayed depressed arcs, indicating non-Debye behavior with distributed grain and grain-boundary contributions. Arrhenius analysis of relaxation maxima yielded activation energies of \(\:\sim\:\) 0.32–0.76 eV, consistent with oxygen-vacancy energies. Raman spectra revealed Co-induced lattice perturbations, including mode broadening/attenuation and red-shifts in the 200–600 cm− 1 range, together with a strengthened stretching feature near 600–650 cm− 1. Kubelka–Munk analysis was utilized to determine the band gaps of the studied samples, 2.19 eV (LFO), 2.29 eV (5% Co), and 2.14 eV (10% Co). Overall, modest Co substitution provides an effective route to tailor vacancy-mediated relaxation and reduce MHz-range dielectric dissipation in LFO-based functional ceramics.