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

Abstract

Nanophosphors are widely used, especially in biological applications in the first and second biological windows. Currently, nanophosphors doped with lanthanide ions (Ln3+) 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 (5D0 → 7F4:Eu3+) and 867 nm, 873 nm, 889 nm, 896 nm, and 907 nm (4F3/2 → 4I9/2:Nd3+) were observed. At 980 nm, 991 nm, 1033 nm (2F5/2 → 2F7/2:Yb3+) and 1048 nm, 1060 nm, 1073 nm, and 1080 nm (4F3/2 → 4I9/2:Nd3+), strong bands of luminescence were visible in the 950 nm–1100 nm range, demonstrating that energy transfer took place.

Synthesis under hydrothermal conditions and structural transformations of nanocrystals in the LaPO4-YPO4-(H2O) system

“…Materials based on nanocrystalline rare-earth phosphates are of significant interest due to their wide range of applications in optics [1][2][3][4], catalysis [2,5,6], medicine [7][8][9], fabrication of gas sensors [10] and other fields [11][12][13]. Special attention is given to the binary-and multi-component systems based on rare-earth orthophosphates, as they are used as luminescent materials [14,15] and matrices for immobilizing toxic and radioactive waste [16][17][18].…”

Effect of the temperature on the luminescence profile of photonic materials for biological applications

“…Glass ceramics were obtained after 15 minutes of heat treatment of the parent glass. Based on previous research [13,15], the co-precipitation method was chosen to fabricate LaPO₄ nanophosphors co-doped with 5% mol of Eu2O3, 5% mol Yb2O5, and 2% mol of Nd2O3. To synthesize the phosphors were used: La2O3, Eu2O3, Yb2O3, Nd2O3 (Sigma-Aldrich, 99.99%), nitric acid (V), NH4H2PO4 (Chempur), and glycerol (Sigma-Aldrich, 99.5%).…”