Search

Two series of Lu2O3:Eu nanocrystalline phosphors were prepared using either combustion procedure with urea fuel or the Pechini procedure. The dopant concentration varied in both series from 0.2 to 13% with respect to Lu. Despite full crystallization and very similar microstructure of materials of both series, we found profound variations in their spectroscopic properties. The combustion-made phosphors were much less efficient emitters and their emission was strongly concentration-quenched above 3% of the dopant content. For the Pechini-derived materials, the concentration quenching was not observed below 10% of the dopant content and even for the dopant concentrations equal to 10 and 13% the quenching was insignificant. In EPR spectra for Gd3+-doped materials, a significant broadening of lines was found for the combustion-made powders. All these observations imply a strong agglomeration of the dopant ions in the specimens made by applying urea fuel in the combustion process. A semi-two-phase composition was suggested in the combustion-prepared powders. In the Pechini-derived nanocrystalline powders, the dopant ions are uniformly, statistically distributed in the host lattice. [Copyright &y& Elsevier]

Decay kinetics and X-ray diffraction patterns of Lu 2 O 3 :Eu with concentration of the dopant spanning 0-20% were measured for two series of materials with crystallites sized of 13 nm and 35 nm. For the series of smaller crystallites a very significant concentration quenching was observed, while for the larger crystallites the effect was minor only. Detailed structural analysis made it possible to postulate that this effect is related to an inhomogeneous distribution of Eu 3+ ions within the smaller crystallites. [ABSTRACT FROM AUTHOR]