Analysis of Excitation Energy Transfer in LaPO4 Nanophosphors Co-Doped with Eu3+/Nd3+ and Eu3+/Nd3+/Yb3+ Ions

Nanophosphors are widely used, especially in biological applications in the first and second biological windows. Currently, nanophosphors doped with lanthanide ions (Ln(3+)) are attracting much attention. However, doping the matrix with lanthanide ions is associated with a narrow luminescence bandwidth. This paper describes the structural and luminescence properties of co-doped LaPO4 nanophosphors, fabricated by the co-precipitation method. X-ray structural analysis, scanning electron microscope measurements with EDS analysis, and luminescence measurements (excitation 395 nm) of LaPO4:Eu3+/Nd3+ and LaPO4:Eu3+/Nd3+/Yb3+ nanophosphors were made and energy transfer between rare-earth ions was investigated. Tests performed confirmed the crystal structure of the produced phosphors and deposition of rare-earth ions in the structure of LaPO4 nanocrystals. In the range of the first biological window (650-950 nm), strong luminescence bands at the wavelengths of 687 nm and 698 nm (D-5(0) -> F-7(4):Eu3+) and 867 nm, 873 nm, 889 nm, 896 nm, and 907 nm (F-4(3/2) -> I-4(9/2):Nd3+) were observed. At 980 nm, 991 nm, 1033 nm (F-2(5/2) -> F-2(7/2):Yb3+) and 1048 nm, 1060 nm, 1073 nm, and 1080 nm (F-4(3/2) -> I-4(9/2):Nd3+), strong bands of luminescence were visible in the 950 nm-1100 nm range, demonstrating that energy transfer took place.

Automated summary

This paper investigates the structural and luminescence properties of co-doped LaPO4 nanophosphors. It is found that LaPO4:Eu3+/Nd3+ and LaPO4:Eu3+/Nd3+/Yb3+ nanophosphors exhibit strong luminescence in the range of 650-1100 nm, indicating energy transfer between rare-earth ions.