Conversion of Valence State and Coordination State of Fe in Transparent Glass‐Ceramics ContainingLi₂ZnSiO₄Nanocrystals

Abstract

Transparent glass-ceramics containing Li 2 ZnSiO 4 :Fe nanocrystals were prepared by melt-quenching method followed by post-heat-treatment process. The as-prepared glasses and glassceramics showed red to near-infrared photoluminescence centered at 730 nm, ascribed to Fe 3+ ions in tetrahedral coordination. The intensity of the photoluminescence was enhanced by two technologically simple techniques-the valence state of irons was controlled from Fe 2+ to Fe 3+ ions using oxidizing agents, whereas the coordination state was compulsorily converted from octahedral to tetrahedral symmetry by performing a ceramization process.

Comment on “Oxygen-Vacancy-Induced Midgap States Responsible for the Fluorescence and the Long-Lasting Phosphorescence of the Inverse Spinel Mg(Mg,Sn)O4”

“…In the meantime, the emission is also close to several reported Fe 3+ emissions in spinel (maximum ∼ 720 nm, fwhm ∼ 1.3 × 10 3 cm –1 ) and feldspar (maxima ∼ 720–750 nm, fwhm ∼ 1.8–2.0 × 10 3 cm –1 ) compounds, and the obtained τ ave falls between the reported Fe 3+ luminescence lifetimes (1–40 ms). ,,− All the above evidence points to the same result that the B band indeed relates to the Fe 3+ impurity. In general, the tetrahedrally coordinated Fe 3+ ions exhibit broadband red–NIR emissions (650–750 nm) in oxides at RT, ,,,,,, while the octahedrally coordinated ones have broadband NIR emissions with longer wavelengths. ,, Therefore, the B band actually originates from the 4 T 1 ( 4 G) → 6 A 1 ( 6 S) transition of the Fe 3+ impurity at the tetrahedral Mg site. And the Fe impurity mainly comes from the Sn source (containing 100 ppm Fe, Table ), because Sn is a siderophile element. , …”

“…10,12,17−20 All the above evidence points to the same result that the B band indeed relates to the Fe 3+ impurity. In general, the tetrahedrally coordinated Fe 3+ ions exhibit broadband red−NIR emissions (650−750 nm) in oxides at RT, 10,12,15,17,18,20,21 while the octahedrally coordinated ones have broadband NIR emissions with longer wavelengths. 19,21,22 Therefore, the B band actually originates from the 4 T 1 ( 4 G) → 6 A 1 ( 6 S) transition of the Fe 3+ impurity at the tetrahedral Mg site.…”

SrAl12O19: Fe3+ @3‐aminopropyl triethoxysilane: Ambient aqueous stable near‐infrared persistent luminescent nanocomposites

“…One is centered at 260 nm in the ultraviolet light region, which is ascribed to charge-transfer state of O 2− →Fe 3+ , and other PLE bands are located in visible region at 405, 509, 563 nm. They are attributed to inter-transitions of Fe 3+ [ 6 A 1 ( 6 S)→ 4 T 2 ( 4 D)],[ 6 A 1 ( 6 S)→ 4 T 2 ( 4 G)], [ 6 A 1 ( 6 S)→ 4 T 1 ( 4 G)] [28][29][30]. The luminescence decay curves (Figure S3)of SrAl 12 O 19 : Fe 3+ N-PLNPs can be fitted by the exponential decay function.…”

Optical studies of mutual redox and partitioning of coordination sites between Ce3+/Ce4+ and Fe2+/Fe3+ ions in Na2O–CaO–SiO2 glass

“…and annealing conditions (time and temperature profile, conditions) [1][2][3][4][5][6][7][8][9][10][11][12]. It is well known that by adding Ce to a glass, the [Fe 2+ ]/[Fe 3+ ] redox ratio decreases, and the glass becomes more transparent to visible light, while its UV-absorption increases [2,3,5,[8][9][10][11][12][13]. However, its effect on the partitioning of Fe 2+ and Fe 3+ between their possible coordination sites has not been widely reported.…”

“…However, its effect on the partitioning of Fe 2+ and Fe 3+ between their possible coordination sites has not been widely reported. The reported absorption spectra and the fitting parameters for the Ce 3+ and Ce 4+ ions vary for different types of glasses, and the fitting parameters are missing in many papers [3,[5][6][7][8][9][10][11][12][13].…”