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<p>The proliferation of wireless communication technologies operating in the S-band (2–4&#xa0;GHz) frequency range has intensified concerns regarding electromagnetic interference (EMI) and potential health risks from prolonged electromagnetic radiation exposure. While perovskite-based materials have emerged as promising microwave absorbers due to their tunable electromagnetic properties, most research has focused on X-band and Ku-band frequencies, leaving S-band absorption mechanisms largely unexplored. Moreover, the fundamental relationship between cation substitution-driven structural transitions and S-band absorption performance remains poorly understood. This study addresses these gaps by investigating Sr²⁺-substituted Ca₁₋ₓSrₓMnO<sub>3</sub> (x = 0.2, 0.5, and 0.8) perovskites synthesized via solid-state reaction assisted by high-energy ball milling. Rietveld refinement reveals that increasing Sr²⁺ content drives a progressive phase transition from mixed orthorhombic–hexagonal structures (x = 0.2 and 0.5) to a single hexagonal phase at x = 0.8, accompanied by reduced crystallite size (50.65&#xa0;nm → 12.98&#xa0;nm) and narrower particle size distribution confirmed by SEM analysis. Magnetic characterization demonstrates predominantly paramagnetic behavior with weak ferromagnetic contributions arising from competing double-exchange and super-exchange interactions. Increasing Sr²⁺ concentration enhances saturation magnetization (0.012 to 0.123 emu/g) while reducing coercivity (0.072 to 0.030 × 10⁴ Oe). Electromagnetic measurements reveal synergistic enhancement of dielectric and magnetic losses with higher Sr²⁺ substitution, resulting in superior microwave absorption. The x = 0.8 composition achieves an optimal reflection loss of − 30.35 dB at 2.24&#xa0;GHz with an effective absorption bandwidth covering 91.5% of the S-band at only 1.5&#xa0;mm thickness, demonstrating exceptional impedance matching. These findings establish Sr-rich Ca₁₋ₓSrₓMnO<sub>3</sub> perovskites as promising candidates for lightweight, broadband S-band electromagnetic interference mitigation.</p>

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Sr²⁺-driven structural transition and enhanced S-band electromagnetic wave absorption in Ca₁₋ₓSrₓMnO₃ perovskites

  • 期刊论文

  • 发表日期：

    2026年7月27日

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  • Yohanes Edi Gunanto,
  • Jan Setiawan,
  • Henni Sitompul,
  • Maya Puspitasari Izaak,
  • Ade Mulyawan,
  • Mashadi,
  • Didin Sahidin Winatapura,
  • Muhammad Rizky Ramdhani,
  • Nanang Sudrajat,
  • Yana Taryana,
  • Ahmad Taufiq,
  • Wisnu Ari Adi,
  • Dianta Ginting,
  • Yunasfi Yunasfi

摘要

The proliferation of wireless communication technologies operating in the S-band (2–4 GHz) frequency range has intensified concerns regarding electromagnetic interference (EMI) and potential health risks from prolonged electromagnetic radiation exposure. While perovskite-based materials have emerged as promising microwave absorbers due to their tunable electromagnetic properties, most research has focused on X-band and Ku-band frequencies, leaving S-band absorption mechanisms largely unexplored. Moreover, the fundamental relationship between cation substitution-driven structural transitions and S-band absorption performance remains poorly understood. This study addresses these gaps by investigating Sr²⁺-substituted Ca₁₋ₓSrₓMnO3 (x = 0.2, 0.5, and 0.8) perovskites synthesized via solid-state reaction assisted by high-energy ball milling. Rietveld refinement reveals that increasing Sr²⁺ content drives a progressive phase transition from mixed orthorhombic–hexagonal structures (x = 0.2 and 0.5) to a single hexagonal phase at x = 0.8, accompanied by reduced crystallite size (50.65 nm → 12.98 nm) and narrower particle size distribution confirmed by SEM analysis. Magnetic characterization demonstrates predominantly paramagnetic behavior with weak ferromagnetic contributions arising from competing double-exchange and super-exchange interactions. Increasing Sr²⁺ concentration enhances saturation magnetization (0.012 to 0.123 emu/g) while reducing coercivity (0.072 to 0.030 × 10⁴ Oe). Electromagnetic measurements reveal synergistic enhancement of dielectric and magnetic losses with higher Sr²⁺ substitution, resulting in superior microwave absorption. The x = 0.8 composition achieves an optimal reflection loss of − 30.35 dB at 2.24 GHz with an effective absorption bandwidth covering 91.5% of the S-band at only 1.5 mm thickness, demonstrating exceptional impedance matching. These findings establish Sr-rich Ca₁₋ₓSrₓMnO3 perovskites as promising candidates for lightweight, broadband S-band electromagnetic interference mitigation.