Luminescence analysis in heavy Mn2+-doped LaMgAl11O19 phosphor: crystallographic site occupation and formation of Mn2+-Mn2+ dimers
【Abstract】
The strategy of heavily doped Mn2+ not only enhances light absorption intensity but also sometimes induces the production of unique long-wavelength luminescence. However, the revelation of the luminescence mechanism remains limited. Herein, we investigate the Mn2+ concentration-dependent luminescence behavior in LaMgAl11O19: xMn2+ (LMAO: xMn2+) phosphor. Upon 450 nm excitation, the PL spectra of LMAO: xMn2+ transition from a single green emission to a dual-wavelength green/far-red emission, ultimately evolving into a pure far-red emission by gradually increasing Mn2+ concentration. The green emission is attributed to tetrahedrally coordinated Mn2+, while the far-red emission originates from the octahedral Mn2+ due to its significantly prolonged lifetime. Notably, an energy transfer occurs between neighboring tetrahedral and octahedral Mn2+, resulting in their similar excitation spectra. Additionally, when the concentration of Mn2+ is further increased, the far-red emission spectrum undergoes a sustained redshift and a broadband NIR luminescence peaking at 830 nm with a shortened lifetime emerges, suggesting its luminescence originates from the 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 heavy Mn2+-doped materials and advanced optical applications.
【Author】
Chenyang Zhan, Haomiao Zhu, Sisi Liang, Yingping Huang, Wendong Nie, Zihao Wang, Maochun Hong
【Journal】
Journal of Materials Chemistry C(IF：6.6) Time：2024-04-16
