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Journal of Nanomaterials
Volume 2009, Article ID 685624, 7 pages
http://dx.doi.org/10.1155/2009/685624
Research Article

Synthesis and Characterization of Upconversion Fluorescent , Doped Cs Nano- and Microcrystals

Institute of Chemistry, University of Osnabrück, Barbarastrasse 7, 49069 Osnabrück, Germany

Received 21 April 2009; Accepted 18 July 2009

Academic Editor: Kui Yu

Copyright © 2009 Helmut Schäfer et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Cs : 78% , 20% , 2% nanocrystals with a mean diameter of approximately 8 nm were synthesized at in the high boiling organic solvent N-(2-hydroxyethyl)-ethylenediamine (HEEDA) using ammonium fluoride, the rare earth chlorides and a solution of caesium alkoxide of N-(2-hydroxyethyl)-ethylenediamine in HEEDA. In parallel with this approach, a microwave assisted synthesis was carried out which forms nanocrystals of the same material, about 50 nm in size, in aqueous solution at /8 bar starting from ammonium fluoride, the rare earth chlorides, and caesium fluoride. In case of the nanocrystals, derived from the HEEDA synthesis, TEM images reveal that the particles are separated but have a broad size distribution. Also an occurred heat-treatment of these nanocrystals ( for 45 minutes) led to bulk material which shows highly efficient light emission upon continuous wave (CW) excitation at 978 nm. Besides the optical properties, the structure and the morphology of the three products were investigated by means of powder XRD and Rietveld method.