The role of amines in the growth of terbium(III)-doped cerium phosphate nanoparticles

Importance of Volume Ratio in Photonic Effects of Lanthanide-Doped LaPO4 Nanocrystals

Experimental variation of the volume ratio (filling factor: i.e., volume of nanoparticles (NPs) compared with that of medium) of nanocomposite materials with doped lanthanide ions demonstrates that it has a significant affect upon local field effects. Lanthanum orthophosphate NPs are doped with Eu³⁺ and/or Tb³⁺ and immersed in organic solvents and lead borate glasses for Tb^{3+ 5} D₄ lifetime measurements. For media with a refractive index (n_med ) less than that of LaPO₄ (n_np = 1.79), the ⁵ D₄ emission decay rate increases with increasing volume ratio of the NPs, whereas for n_med > 1.79, the decay rate decreases with increasing volume ratio. Fitting with the model of Pukhov provides an estimation of the radiative lifetime of ⁵ D₄ and the quantum yield. Energy transfer (ET) from Tb³⁺ to Eu³⁺ occurs in co-doped LaPO₄ NPs with excitation into a Tb³⁺ absorption band. The ET rate is independent on n_med and the energy transfer efficiency decreases with an increase in n_med . The behavior of ET rate with regard to the local field is consistent with the Dexter, but not Förster, equation for ET rate involving the electric dipole-electric dipole mechanism. This has consequences when using the spectroscopic ruler approach to measure distances between donor-acceptor chromophores.

Incorporation of Ln-Doped LaPO4 Nanocrystals as Luminescent Markers in Silica Nanoparticles

Lanthanide ions are promising for the labeling of silica nanoparticles with a specific luminescent fingerprint due to their sharp line emission at characteristic wavelengths. With the increasing use of silica nanoparticles in consumer products, it is important to label silica nanoparticles in order to trace the biodistribution, both in the environment and living organisms.In this work, we synthesized LaPO4 nanocrystals (NCs) with sizes ranging from 4 to 8 nm doped with europium or cerium and terbium. After silica growth using an inverse micelle method, monodisperse silica spheres were obtained with a single LaPO4 NC in the center. We demonstrate that the size of the silica spheres can be tuned in the 25-55 nm range by addition of small volumes of methanol during the silica growth reaction. Both the LaPO4 core and silica nanocrystal showed sharp line emission characteristic for europium and terbium providing unique optical labels in silica nanoparticles of variable sizes.

Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors

Polyethyleneimine (PEI) functionalized multicolor luminescent LaF(3) nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb(3+) and Eu(3+)), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu(3+) versus Tb(3) +) and the molar ratio of the two doping ions.