Three glass systems CaO-B2O3-MO (MO = Al2O3, Sb2O3, and Bi2O3) doped with small concentrations of Cu nanoparticles were synthesized by the melt-quenching technique. The prepared glasses were denoted as AlCu, SbCu, and BiCu, respectively. The physical properties, UV–visible absorption, and photoluminescence experimental studies are reported in the present study. The density (ρ) of the glass samples increased gradually (from 2.673 g/cm3 to 2.868 g/cm3) in the order AlCu < SbCu < BiCu. As a result, the boron–boron separation (dB–B) was found to be the lowest and the oxygen packing density (OPD) was found to be the highest for the glass sample BiCu. The x-ray photoelectron spectroscopy (XPS) spectrum of Cu (2p) confirmed the presence of three stable ionic states of copper (Cu0, Cu+ and Cu2+) showing the first band at ~932.6 eV (Cu 2p3/2) and the second band at ~952.4 eV (Cu 2p1/2) associated with spin and orbital angular momentum. The copper nanoclusters were absent in the present glass hosts. During melt-quenching, the copper nanoparticles were dissolved, forming oxygen complexes in the form of [CuO4] and [CuO6] in the glass matrix. UV–visible–near-infrared absorption spectra of the samples revealed a charge-transfer transition (3d10 → 3d94s1) of Cu+ ions and a ligand-to-metal charge–transfer (LMCT) transition O2− → Cu2+ in the UV region (330–390 nm), and a broad absorption band with a peak value around 665–685 nm in the visible region due to localized electronic transition (2B1g → 2B2g) of Cu2+ ions in the present glass hosts. The optical bandgap (Eo) and Urbach energy (Eu) of the samples were found to be in the range of 3.02–3.24 eV and 0.406–0.454 eV, respectively. The photoluminescence spectra presented two clear emission bands at about 450 nm and 550 nm, attributed to d–d transitions of isolated Cu+ ions and Cu+–Cu+/Cu+–Cu2+ ion pairs, respectively. The CIE chromaticity diagram illustrates the emission of light in the blue-green region. The correlated color temperature (CCT) decreases from AlCu to BiCu (i.e., from 16,645 K to 14,097 K), reflecting a color transition due to the modifier effect. Thus, these glasses have possible applications in optical switching, warm light-emitting diodes (LEDs), and solid-state lighting applications. Graphical Abstract Ternary diagram and CIE chromacity diagram of 33CaO-65B2O3-1MO (MO=Al2O3, Sb2O3, and Bi2O3)-1Cu glasses

Evaluation of UV–Visible Absorption, X-ray Photoelectron Spectroscopic Profiles and Blue-Green Emission Transitions of Cu⁺/Cu²⁺ Ions in CaO-B₂O₃-MO (MO = Al₂O_3, Sb₂O_3, and Bi₂O₃) Glass Hosts for Solid-State Lighting Applications

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发表日期：

2026年6月29日

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N. Suresh Kumar,
Linganaboina Srinivasa Rao,
D. Nagendra Prasad,
Ch. Murali Krishna

摘要

Three glass systems CaO-B₂O₃-MO (MO = Al₂O_3, Sb₂O_3, and Bi₂O₃) doped with small concentrations of Cu nanoparticles were synthesized by the melt-quenching technique. The prepared glasses were denoted as AlCu, SbCu, and BiCu, respectively. The physical properties, UV–visible absorption, and photoluminescence experimental studies are reported in the present study. The density (ρ) of the glass samples increased gradually (from 2.673 g/cm³ to 2.868 g/cm³) in the order AlCu < SbCu < BiCu. As a result, the boron–boron separation (d_B–B) was found to be the lowest and the oxygen packing density (OPD) was found to be the highest for the glass sample BiCu. The x-ray photoelectron spectroscopy (XPS) spectrum of Cu (2p) confirmed the presence of three stable ionic states of copper (Cu⁰, Cu⁺ and Cu²⁺) showing the first band at ~932.6 eV (Cu 2p_3/2) and the second band at ~952.4 eV (Cu 2p_1/2) associated with spin and orbital angular momentum. The copper nanoclusters were absent in the present glass hosts. During melt-quenching, the copper nanoparticles were dissolved, forming oxygen complexes in the form of [CuO₄] and [CuO₆] in the glass matrix. UV–visible–near-infrared absorption spectra of the samples revealed a charge-transfer transition (3d¹⁰ → 3d⁹4s¹) of Cu⁺ ions and a ligand-to-metal charge–transfer (LMCT) transition O²⁻ → Cu²⁺ in the UV region (330–390 nm), and a broad absorption band with a peak value around 665–685 nm in the visible region due to localized electronic transition (²B_1g → ²B_2g) of Cu²⁺ ions in the present glass hosts. The optical bandgap (E_o) and Urbach energy (E_u) of the samples were found to be in the range of 3.02–3.24 eV and 0.406–0.454 eV, respectively. The photoluminescence spectra presented two clear emission bands at about 450 nm and 550 nm, attributed to d–d transitions of isolated Cu⁺ ions and Cu⁺–Cu⁺/Cu⁺–Cu²⁺ ion pairs, respectively. The CIE chromaticity diagram illustrates the emission of light in the blue-green region. The correlated color temperature (CCT) decreases from AlCu to BiCu (i.e., from 16,645 K to 14,097 K), reflecting a color transition due to the modifier effect. Thus, these glasses have possible applications in optical switching, warm light-emitting diodes (LEDs), and solid-state lighting applications.

Graphical Abstract

Ternary diagram and CIE chromacity diagram of 33CaO-65B2O3-1MO (MO=Al₂O₃, Sb₂O₃, and Bi₂O₃)-1Cu glasses

Evaluation of UV–Visible Absorption, X-ray Photoelectron Spectroscopic Profiles and Blue-Green Emission Transitions of Cu+/Cu2+ Ions in CaO-B2O3-MO (MO = Al2O3, Sb2O3, and Bi2O3) Glass Hosts for Solid-State Lighting Applications

摘要

Evaluation of UV–Visible Absorption, X-ray Photoelectron Spectroscopic Profiles and Blue-Green Emission Transitions of Cu⁺/Cu²⁺ Ions in CaO-B₂O₃-MO (MO = Al₂O_3, Sb₂O_3, and Bi₂O₃) Glass Hosts for Solid-State Lighting Applications