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<p>In this work, Sr-doped Ruddlesden–Popper nickelates, La<sub>2-<i>y</i></sub>Sr<sub><i>y</i></sub>NiO<sub>4-δ</sub> (<i>y</i> = 0.25, 0.5, and 1.0), are investigated for microwave absorption applications. Tetragonal layered structures are confirmed by X-ray diffraction, while electron paramagnetic resonance and magnetic hysteresis measurements reveal that moderate Sr substitution induces weak ferromagnetic behavior, whereas higher Sr contents suppress magnetic ordering, leading to paramagnetic- or diamagnetic-like characteristics. Among the investigated compositions, the y = 0.25 sample exhibits the best impedance matching (|Z<sub>in</sub>/Z<sub>0</sub>| ≈ 1), delivering an ultralow RL<sub>min</sub> of − 89 dB at a matching thickness of 0.9 mm and an effective absorption bandwidth of 2.1 GHz in the X-band. In contrast, higher Sr concentrations are associated with reduced dielectric loss and weaker absorption, likely due to changes in defect structure and charge-transport pathways. These results demonstrate that controlled Sr doping effectively tunes electromagnetic dissipation in layered nickelates, highlighting La<sub>2-<i>y</i></sub>Sr<sub><i>y</i></sub>NiO<sub>4-δ</sub> as a promising candidate for microwave absorption applications.</p>

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Enhanced microwave absorption in Sr-doped Ruddlesden–Popper lanthanum nickelates

  • 期刊论文

  • 发表日期：

    2026年5月8日

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  • Akbar Khan,
  • Raz Muhammad,
  • M. Arshad Farhan,
  • Hafiz Zahid Shafi,
  • Dandan Han,
  • Bagh Hussain

摘要

In this work, Sr-doped Ruddlesden–Popper nickelates, La2-ySryNiO4-δ (y = 0.25, 0.5, and 1.0), are investigated for microwave absorption applications. Tetragonal layered structures are confirmed by X-ray diffraction, while electron paramagnetic resonance and magnetic hysteresis measurements reveal that moderate Sr substitution induces weak ferromagnetic behavior, whereas higher Sr contents suppress magnetic ordering, leading to paramagnetic- or diamagnetic-like characteristics. Among the investigated compositions, the y = 0.25 sample exhibits the best impedance matching (|Zin/Z0| ≈ 1), delivering an ultralow RLmin of − 89 dB at a matching thickness of 0.9 mm and an effective absorption bandwidth of 2.1 GHz in the X-band. In contrast, higher Sr concentrations are associated with reduced dielectric loss and weaker absorption, likely due to changes in defect structure and charge-transport pathways. These results demonstrate that controlled Sr doping effectively tunes electromagnetic dissipation in layered nickelates, highlighting La2-ySryNiO4-δ as a promising candidate for microwave absorption applications.