Na2MgAlF7:Ln3+ (Ln3+ = Ce, Gd) weberite downshifting phosphor for designing UVB LED

• Published in: Journal of materials science Vol. 59; no. 34; pp. 16158 - 16169
• Main Authors: Dhale, Shruti Prabhakar, Ugemuge, N. S., Singh, Vartika, Moharil, S. V.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2024; Springer Nature B.V
• Subjects: Cerium; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Electronic Materials; Electrons; Excitation spectra; Gadolinium; Light emitting diodes; Materials Science; Phosphors; Polymer Sciences; Solid Mechanics; Ultraviolet emission
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-024-10131-7

New results on luminescence of Na 2 MgAlF 7 activated with Ce 3+ and/or Gd 3+ are presented. Powder XRD confirms orthorhombic structure with Imm2 space group. Intense ultraviolet (UV) emission is observed for both the phosphors. Excitation for Gd 3+ is in the form of narrow lines while a broad band marks the excitation spectrum for Ce 3+ . This broad band covers the most intense excitation line for Gd 3+ . By virtue of the close proximity of Ce 3+ and Gd 3+ absorption, the former can act as a sensitizer for the latter. The excitation spectrum for Ce 3+ also overlaps the emission from 275 nm UV chip. This was exploited for constructing phosphor converted UVB LED. Using Na 2 MgAlF 7 :Ce 3+ phosphor and 275 nm UV chip, LED emitting broad band UVB light is demonstrated. Coating 275 nm chip with Na 2 MgAlF 7 :Ce 3+ , Gd 3+ phosphor, resulted in a LED with dominant emission at 311 nm. The results presented are important for obtaining UVB LEDs at lower prices. Graphical abstract