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<p>Perovskite oxides such as LaFeO₃ are promising for various functional applications, with performance significantly enhanced by targeted doping strategies. This study reports the synthesis of La₀.₈Sr₀.₁Ba₀.₁Fe₁₋ₓNiₓO₃ (x = 0.05 and 0.1) compounds via the sol–gel method, followed by systematic structural, microstructural, electrical, and dielectric characterizations using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and impedance spectroscopy. XRD results confirmed the formation of a single-phase rhombohedral perovskite structure. SEM analysis revealed a homogeneous microstructure, with average grain size decreasing from 171&#xa0;nm (x = 0.05) to 119&#xa0;nm (x = 0.1), attributed to the grain growth pinning effect of Ni. Raman and FTIR spectroscopies indicated that Ni substitution induces local lattice distortion. Electrical characterization showed semiconducting behavior across compositions, with DC conductivity analysis revealing temperature-dependent conduction mechanisms: Mott Variable Range Hopping (VRH) at low temperatures, Greaves VRH at intermediate, and Small Polaron Hopping (SPH) at higher temperatures. Activation energy decreased with increasing Ni doping. AC conductivity analysis demonstrated correlated barrier hopping (CBH) conduction for x = 0.05 and overlapping large polaron tunneling (OLPT) for x = 0.1 at high frequencies. Dielectric measurements showed reduced dielectric constant and loss upon Ni substitution, while impedance spectroscopy revealed non-Debye relaxation processes dominated by grain and grain boundary contributions. These findings establish that Ni doping effectively modulates structural order, defect chemistry, and charge transport in La₀.₈Sr₀.₁Ba₀.₁FeO₃ perovskites, improving their electrical performance and dielectric properties and making them promising candidates for applications in solid oxide fuel cells, gas sensors, and electronic devices.</p>

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Ni-Doping Effects on Structural, Electrical, and Dielectric Properties of LaFeO₃ Perovskites for Multifunctional Applications

  • 期刊论文

  • 发表日期：

    2026年5月20日

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  • Houcine Dhahri,
  • Nessrine Mechi,
  • Aref Omri,
  • Mohamed Houcine Dhaou,
  • M. A. Ghebouli,
  • B. F. O. Costa,
  • Hazem F. Sakeek,
  • Kamel Khirouni

摘要

Perovskite oxides such as LaFeO₃ are promising for various functional applications, with performance significantly enhanced by targeted doping strategies. This study reports the synthesis of La₀.₈Sr₀.₁Ba₀.₁Fe₁₋ₓNiₓO₃ (x = 0.05 and 0.1) compounds via the sol–gel method, followed by systematic structural, microstructural, electrical, and dielectric characterizations using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and impedance spectroscopy. XRD results confirmed the formation of a single-phase rhombohedral perovskite structure. SEM analysis revealed a homogeneous microstructure, with average grain size decreasing from 171 nm (x = 0.05) to 119 nm (x = 0.1), attributed to the grain growth pinning effect of Ni. Raman and FTIR spectroscopies indicated that Ni substitution induces local lattice distortion. Electrical characterization showed semiconducting behavior across compositions, with DC conductivity analysis revealing temperature-dependent conduction mechanisms: Mott Variable Range Hopping (VRH) at low temperatures, Greaves VRH at intermediate, and Small Polaron Hopping (SPH) at higher temperatures. Activation energy decreased with increasing Ni doping. AC conductivity analysis demonstrated correlated barrier hopping (CBH) conduction for x = 0.05 and overlapping large polaron tunneling (OLPT) for x = 0.1 at high frequencies. Dielectric measurements showed reduced dielectric constant and loss upon Ni substitution, while impedance spectroscopy revealed non-Debye relaxation processes dominated by grain and grain boundary contributions. These findings establish that Ni doping effectively modulates structural order, defect chemistry, and charge transport in La₀.₈Sr₀.₁Ba₀.₁FeO₃ perovskites, improving their electrical performance and dielectric properties and making them promising candidates for applications in solid oxide fuel cells, gas sensors, and electronic devices.