Regensburg 2007 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 10: Dielectric and Ferroelectric Thin Films and Nanostructures III

DF 10.7: Talk

Thursday, March 29, 2007, 16:30–16:50, H48

Crystal Phase Control of Luminescing alpha-NaGdF4:Eu3+ and beta-NaGdF4:Eu3+ Nanocrystals — •Pavel Ptacek, Helmut Schäfer, Karsten Kömpe, and Markus Haase — Institute of Chemistry, University of Osnabrück, Barbarastraße 7, D-49076 Osnabrück

NaGdF4:Eu3+, NaEuF4, and NaGdF4 nanocrystals with mean particle sizes between 11 and 15 nm were synthesized in the high-boiling coordinating solvent 2-Hydroxyethyl ethylenediamine (HEEDA) under very similar reaction conditions. Phase pure nanomaterials, crystallizing either in the cubic alpha-phase or the hexagonal beta-phase, were obtained by adjusting one reaction parameter only, i.e. the molar ratio between metal and fluoride ions in the synthesis. The hexagonal beta-phase is formed, if this molar ratio is close to stoichiometric, whereas the cubic alpha-phase is obtained in the presence of excess metal ions. The optical properties of the Eu3+ doped samples are different for the two crystal phases. The results indicate an increased number of oxygen impurities close to Eu3+ ions, if excess metal ions are used in the synthesis.

Supported by the Deutsche Forschungsgemeinschaft