Work

Enhancing near‑infrared luminescence in Fe3+‑doped Na‑β‑Al2O3 phosphors via cation substitution for LED application

Year: 2026

Type: article

Abstract: The transition-metal ion Fe 3+ is a promising near-infrared (NIR) activator due to its tunable emission, low cost, and non-toxicity. However, developing Fe 3+ -doped NIR phosphors with well-rounded performance remains challenging because of the parity-forbidden nature of the d-d transition of Fe 3+ . In this work, a series of NaM 11 O 17 :Fe 3+ (M = Al, Ga) NIR phosphors were synthesized via a solid-state reaction method. A cation-substitution strategy was employed, where replacing the larger Ga 3+ with smaller Al 3+ induces lattice contraction and coordination polyhedron distortion. This lowers the site symmetry around Fe 3+ , effectively relaxing the spin-forbidden d-d transition of Fe 3+ and thereby enhancing the overall luminescence. The optimized phosphor exhibits a 13-fold increase in NIR emission intensity, an internal quantum efficiency (IQE) improvement from 18.2% to 62.9%, and enhanced thermal stability (71.8% intensity retention at 423 K vs. 22.1%). Finally, an NIR phosphor-converted light-emitting diode (pc-LED) fabricated with the optimized NaAl 11 O 17 :Fe 3+ (NAO:Fe 3+ ) phosphor and a 365 nm chip demonstrates promising potential for applications in NIR imaging and the detection of Cu 2+ in aqueous solutions.

Source: Journal of Alloys and Compounds

DOI: 10.1016/j.jallcom.2026.189446