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<p>High-purity α-Al2O3 nanoparticles were synthesised using a modified Pechini sol–gel method and calcinated at 1100 °C. Their structural, optical, and dielectric properties were thoroughly examined. Structure research utilizing X-ray diffraction and advanced Rietveld refinement showed that adding the axial divergence asymmetry pseudo-Voigt function improves refinement quality and produces more precise crystallographic parameters for the R-3c corundum structure. A stress-free crystalline framework was confirmed by a size-strain plot showing a volume-weighted crystallite size of ~ 24.4 nm and low lattice strain. The HR-TEM revealed spherical polycrystalline aggregates with an average particle size of ~ 100 nm, while FTIR confirmed phase purity and complete organic precursor elimination. UV–Vis diffuse reflectance spectroscopy determined the refractive index, extinction coefficient, absorption coefficient, and complex dielectric function. The Kubelka–Munk formalism estimated the optical band gap at ~ 4.29 eV, indicating wide-band-gap insulating behaviour. In the visible-near-infrared region, the real part of the dielectric constant showed substantial photon energy dispersion, but the imaginary part remained extremely low (≤ 0.03), indicating minimal optical losses. The dielectric loss tangent was extremely low (~ 10–4–10–6), indicating strong electronic polarization and minimal dissipation. The lattice dielectric constant (εₗ = 7.97), low plasma frequency, and minimal free-carrier contribution support the intrinsic insulation of α-Al2O3. Researchers found a strong correlation between structural perfection and low-loss optical response, making α-Al2O3 nanoparticles promising for high-transparency, dielectric-stable applications such as optical coatings, ultraviolet optoelectronic devices, and high-frequency photonics.</p>

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Integrated structural, optical and dielectric analysis of low-loss α-Al₂O₃ nanoparticles for UV photonic and dielectric applications

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月11日

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  • Sara A. Mohamed,
  • Abdalrahman M. Rayan,
  • A M Abdel Hakeem,
  • S. H. Mohamed,
  • A. M. Abd El-Rahman,
  • Khater A. E. Gad,
  • Mahrous R. Ahmed,
  • Naglaa AbdelAll

摘要

High-purity α-Al2O3 nanoparticles were synthesised using a modified Pechini sol–gel method and calcinated at 1100 °C. Their structural, optical, and dielectric properties were thoroughly examined. Structure research utilizing X-ray diffraction and advanced Rietveld refinement showed that adding the axial divergence asymmetry pseudo-Voigt function improves refinement quality and produces more precise crystallographic parameters for the R-3c corundum structure. A stress-free crystalline framework was confirmed by a size-strain plot showing a volume-weighted crystallite size of ~ 24.4 nm and low lattice strain. The HR-TEM revealed spherical polycrystalline aggregates with an average particle size of ~ 100 nm, while FTIR confirmed phase purity and complete organic precursor elimination. UV–Vis diffuse reflectance spectroscopy determined the refractive index, extinction coefficient, absorption coefficient, and complex dielectric function. The Kubelka–Munk formalism estimated the optical band gap at ~ 4.29 eV, indicating wide-band-gap insulating behaviour. In the visible-near-infrared region, the real part of the dielectric constant showed substantial photon energy dispersion, but the imaginary part remained extremely low (≤ 0.03), indicating minimal optical losses. The dielectric loss tangent was extremely low (~ 10–4–10–6), indicating strong electronic polarization and minimal dissipation. The lattice dielectric constant (εₗ = 7.97), low plasma frequency, and minimal free-carrier contribution support the intrinsic insulation of α-Al2O3. Researchers found a strong correlation between structural perfection and low-loss optical response, making α-Al2O3 nanoparticles promising for high-transparency, dielectric-stable applications such as optical coatings, ultraviolet optoelectronic devices, and high-frequency photonics.