Issue 19, 2024

Luminescence analysis of heavily Mn2+-doped LaMgAl11O19 phosphors: crystallographic site occupation and the formation of Mn2+–Mn2+ dimers

Abstract

The strategy of heavily doping Mn2+ not only enhances light-absorption intensity, but also sometimes induces the production of unique long-wavelength luminescence. However, the understanding of the luminescence mechanism remains limited. Herein, we investigated the Mn2+ concentration-dependent luminescence behavior of LaMgAl11O19: xMn2+ (LMAO : xMn2+) phosphors. Upon an excitation of 450 nm, the PL spectra of LMAO : xMn2+ transitioned from single green emission to dual-wavelength green/far-red emission, ultimately evolving into pure far-red emission by gradually increasing Mn2+ concentration. The green emission was attributed to tetrahedrally coordinated Mn2+, whereas the far-red emission originated from octahedral Mn2+ owing to its significantly prolonged lifetime. Notably, an energy transfer occurred between neighboring tetrahedral and octahedral Mn2+, resulting in their similar excitation spectra. Additionally, when the concentration of Mn2+ was further increased, the far-red emission spectrum underwent a sustained redshift, and broadband NIR luminescence peaking at 830 nm with a shortened lifetime emerged, suggesting its luminescence originates from Mn2+–Mn2+ dimers. Finally, leveraging the similar excitation spectra and distinct thermal quenching behaviors of the green and far-red emissions, we developed a novel FIR thermometer LMAO : 0.54Mn2+ demonstrating excellent temperature-sensing capability and repeatability. This study provides new insights into the heavily Mn2+-doped materials and advanced optical applications.

Graphical abstract: Luminescence analysis of heavily Mn2+-doped LaMgAl11O19 phosphors: crystallographic site occupation and the formation of Mn2+–Mn2+ dimers

Supplementary files

Article information

Article type
Paper
Submitted
05 Mar 2024
Accepted
13 Apr 2024
First published
16 Apr 2024

J. Mater. Chem. C, 2024,12, 6932-6942

Luminescence analysis of heavily Mn2+-doped LaMgAl11O19 phosphors: crystallographic site occupation and the formation of Mn2+–Mn2+ dimers

C. Zhan, H. Zhu, S. Liang, Y. Huang, W. Nie, Z. Wang and M. Hong, J. Mater. Chem. C, 2024, 12, 6932 DOI: 10.1039/D4TC00890A

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