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<p>A systematic investigation was carried out on Sm<sup>3+</sup>-activated calcium zinc borosilicate (CaZnBSi) glass samples containing 0.1–2.0&#xa0;mol% Sm<sup>3+</sup> ions, synthesized via the conventional melt-quenching technique. The novelty of the present work lies in establishing a comprehensive correlation between dopant concentration, structural modification, optical band gap tuning, and photoluminescence behavior within a single glass system. X-ray diffraction (XRD) patterns confirmed the amorphous nature of all compositions, while FT-IR analysis revealed the evolution of borate structural units and network connectivity. With increasing Sm<sup>3+</sup> ions concentration, both direct and indirect optical band gap values decreased from 3.52 to 3.38&#xa0;eV and 2.99 to 2.68&#xa0;eV, respectively, attributed to increased non-bridging oxygen formation and enhanced structural disorder. Nephelauxetic ratio and bonding parameter analysis indicated a progressive increase in the covalent nature of Sm-O bonds. Under 402&#xa0;nm excitation, the glasses exhibited intense reddish-orange emission dominated by the hypersensitive transition (<sup>4</sup>G<sub>5/2</sub> → <sup>6</sup>H<sub>7/2</sub>). The emission intensity reached a maximum at 0.5&#xa0;mol% Sm<sup>3+</sup> and decreased at higher concentrations due to concentration quenching. The quenching mechanism was systematically analyzed using Dexter theory, confirming dipole-dipole interaction as the dominant energy transfer process. Temperature-dependent photoluminescence studies demonstrated excellent thermal stability, with ~ 75% emission intensity retained at 443&#xa0;K and an activation energy of 0.358&#xa0;eV. The obtained CIE chromaticity coordinates lie in the warm-white region with correlated color temperature values around 1875–1910&#xa0;K. These results establish Sm<sup>3+</sup>-doped CaZnBSi glasses as promising candidates for warm-white light-emitting diodes (w-LEDs) and advanced photonic applications.</p>

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Concentration-dependent structural, optical, and photoluminescence properties of Sm3+-doped CaZnBSi glasses for warm-white LED applications

  • 期刊论文

  • 发表日期：

    2026年5月26日

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  • Seema,
  • Bhawna,
  • Ankit,
  • Anu,
  • Kamal Kishor,
  • A. S. Rao

摘要

A systematic investigation was carried out on Sm3+-activated calcium zinc borosilicate (CaZnBSi) glass samples containing 0.1–2.0 mol% Sm3+ ions, synthesized via the conventional melt-quenching technique. The novelty of the present work lies in establishing a comprehensive correlation between dopant concentration, structural modification, optical band gap tuning, and photoluminescence behavior within a single glass system. X-ray diffraction (XRD) patterns confirmed the amorphous nature of all compositions, while FT-IR analysis revealed the evolution of borate structural units and network connectivity. With increasing Sm3+ ions concentration, both direct and indirect optical band gap values decreased from 3.52 to 3.38 eV and 2.99 to 2.68 eV, respectively, attributed to increased non-bridging oxygen formation and enhanced structural disorder. Nephelauxetic ratio and bonding parameter analysis indicated a progressive increase in the covalent nature of Sm-O bonds. Under 402 nm excitation, the glasses exhibited intense reddish-orange emission dominated by the hypersensitive transition (4G5/2 → 6H7/2). The emission intensity reached a maximum at 0.5 mol% Sm3+ and decreased at higher concentrations due to concentration quenching. The quenching mechanism was systematically analyzed using Dexter theory, confirming dipole-dipole interaction as the dominant energy transfer process. Temperature-dependent photoluminescence studies demonstrated excellent thermal stability, with ~ 75% emission intensity retained at 443 K and an activation energy of 0.358 eV. The obtained CIE chromaticity coordinates lie in the warm-white region with correlated color temperature values around 1875–1910 K. These results establish Sm3+-doped CaZnBSi glasses as promising candidates for warm-white light-emitting diodes (w-LEDs) and advanced photonic applications.