Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Crystallization, Nucleation and Self Assembly I

CPP 14.9: Vortrag

Dienstag, 12. März 2013, 11:45–12:00, H39

Influence of Organic Ligands on ZnO Nanoparticle Formation via in-situ XRD — •Mirijam Zobel and Reinhard B. Neder — Lehrstuhl für Kristallographie und Strukturphysik, Universität Erlangen

Organic ligands are used in solvent-based sol-gel processes to synthesize monodisperse, metal oxide nanoparticles for semiconductor industry. The ligand type and chemistry have a decisive influence not only on the particle size, but also on the structure and kinetics during the nucleation. Using high-energy synchrotron radiation, it is possible to study this nucleation in-situ via x-ray wide angle diffraction, even in salt solutions with very low concentration (30 mM). Our model system zinc oxide exhibits a precursor structure of the metal salt, which is stable for several hours and exists both without and in presence of additional ligands, e.g. dimethyl-L-tartrate or pentantrione. Addition of an alkali results in an instantaneous transformation into larger precursor structures, which - after a further ligand-specific ripening time - again spontaneously start to nucleate to approx. 2 nm nanoparticles. This final nucleation of the particles surprisingly takes several hours. Here we report for the first time that such an in-situ high-energy x-ray wide angle diffraction experiment with synchrotron radiation is possible and that it reveals the phase formation and the growth of nanoparticles within organic solvents. By deducing the pair distribution function and hence the structure of the different phases present, more profound structure analysis can subsequently be carried out.