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<p>Nanocrystalline boron carbide (B₄C) was probed by room-temperature X-band EPR before and after controlled neutron exposure to reveal irradiation-driven changes in defect populations and local symmetry. Pristine powders show a multi-component spectrum with an orthorhombic g-tensor. With increasing neutron fluence (10¹⁵–10¹⁷ n·cm⁻²), the response converges to a stronger, more symmetric resonance near g ≈ 2.00 that exhibits clear peak-to-peak broadening (ΔB<sub>pp</sub>). These trends are consistent with boron transmutation—dominantly ¹⁰B(n,α)⁷Li and, secondarily, ¹¹B(n,γ)→¹²B→¹²C—creating vacancies and defect complexes, increasing spin concentration, enhancing dipolar interactions, and partially averaging g-anisotropy. Carbon channels are negligible at thermal energies. The results provide a concise, mechanism-anchored picture of defect evolution in irradiated B₄C and establish g, ΔB<sub>pp</sub>, and integrated intensity as practical spectral markers for monitoring neutron-induced changes in boron-rich ceramics.</p>

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Neutron-Induced Effects on Paramagnetic Centers in Nanocrystalline Boron Carbide (B₄C)

  • 期刊论文

  • 发表日期：

    2026年2月14日

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  • Elchin M. Huseynov,
  • Jale G. Atakishiyeva,
  • Adil A. Garibov,
  • Rashid C. Gasimov,
  • Mahammad A. Bayramov,
  • Huseyn J. Huseynov,
  • Ilaha V. Izzatova,
  • Raisa R. Hakhiyeva

摘要

Nanocrystalline boron carbide (B₄C) was probed by room-temperature X-band EPR before and after controlled neutron exposure to reveal irradiation-driven changes in defect populations and local symmetry. Pristine powders show a multi-component spectrum with an orthorhombic g-tensor. With increasing neutron fluence (10¹⁵–10¹⁷ n·cm⁻²), the response converges to a stronger, more symmetric resonance near g ≈ 2.00 that exhibits clear peak-to-peak broadening (ΔBpp). These trends are consistent with boron transmutation—dominantly ¹⁰B(n,α)⁷Li and, secondarily, ¹¹B(n,γ)→¹²B→¹²C—creating vacancies and defect complexes, increasing spin concentration, enhancing dipolar interactions, and partially averaging g-anisotropy. Carbon channels are negligible at thermal energies. The results provide a concise, mechanism-anchored picture of defect evolution in irradiated B₄C and establish g, ΔBpp, and integrated intensity as practical spectral markers for monitoring neutron-induced changes in boron-rich ceramics.