Lanthanide-Doped Nanoparticles with Excellent Luminescent Properties in Organic Media

Abstract

Surface-coated nanoparticles of LaF 3 and LaPO 4 doped with the luminescent trivalent lanthanide ions Eu 3+ , Nd 3+ , Er 3+ , Pr 3+ , Ho 3+ , and Yb 3+ have been prepared. These ions emit in the visible and in the near-infrared part of the electromagnetic spectrum. The ions Nd 3+ , Er 3+ , Pr 3+ , and Ho 3+ are the main focus in this research because they show emissions in telecommunication windows. The Yb 3+ ion is of interest because it can be used as a sensitizer for Er 3+ . The Eu 3+ ion has been used as a probe for the structural environment of the luminescent ion. It is shown that these lanthanide ions are incorporated in the inorganic host of the particles and that the particles are dispersable in organic solvents. The luminescent lifetimes of the ions are increased by orders of magnitude compared to organic complexes, with values ranging from several microseconds for Pr 3+ and Ho 3+ , up to about 200 µs for Nd 3+ , and 1 ms for Er 3+ . This increase in the luminescence lifetime is indicative of an effective shielding of the lanthanide ions from nonradiative decay of the excited state by the high-energy vibrations of the solvents and the coordinated organic ligands. A model is proposed to describe the nonexponential behavior of the luminescence decay by quenching from outside the particle. It uses two fit parameters, k R , a parameter describing the luminescence decay rate in the absence of surface quenching, and C, a parameter describing the sensitivity toward quenching. Using this model, the luminescence decays can be fitted very well, and factors influencing the luminescence lifetime like concentration quenching and solvent effects can be described accurately.

Physical Background for Luminescence Thermometry Sensors Based on Pr3+:LaF3 Crystalline Particles

“…The luminescent spectra have the emissions bands at about 487, 523, 537, 580, 601, and 672 nm which are interpreted as a result of the transition from the 3 P ( = 0, 1, 2) excited states which is 2 times less than one for YAG (700-865 cm −1 ). Indeed to bridge the 3 P 0 -1 D 2 energy gap, the 9 phonons are required in case of LaF 3 and only 4 or 5 ones for YAG; thus, the multiphonon relaxation is expected negligible [21,30]. Moreover, the electron phonon coupling constants of YAG are highly different from those of LaF 3 [21].…”

Observation of intermediate bands in Eu3+ doped YPO4 host: Li+ ion effect and blue to pink light emitter

“…2,25,26 But in some cases, the intensity of electric dipole transition is predominant over magnetic dipole transition in Eu 3+ doped (Y/La)PO 4 /YPO 4 .nH 2 O, which is expected from the theoretical view on site symmetry of Y 3+ where Eu 3+ ions occupy. [27][28][29][30][31][32] Existence of intermediate bands observed in YPO 4 system has not been discussed much in literature. This understanding will be useful in transfer process from such intermediate bands to Eu 3+ .…”

Characterization of CBD-CdS Doped with Some Rare Earths III (Eu3+,Ce3+) as Function of Synthesis Time

“…Inorganic compounds doped with lanthanide ions are widely used as the luminescent materials in lighting 1 and displays 2 , optical amplifiers 3 and lasers 4 . Recently, the optical properties of nanocrystals doped with lanthanide impurities have attracted much attention because of they are expected to modify both electronic states and electromagnetic fields.…”