Berlin 2018 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 27: Postersession KFM

KFM 27.28: Poster

Donnerstag, 15. März 2018, 15:00–17:00, Poster E

High-resolution structural and chemical analysis of transition metal oxide nanoparticles — •Aladin Ullrich, Daniel Schmidtner, Mohammad Mostafizar Rahman, and Siegfried Horn — University of Augsburg, 86159 Augsburg, Germany

We have investigated the structural and chemical composition of pure iron oxide and manganese ferrite nanoparticles by transmission electron microscopy (TEM). The particles were synthesized by thermal decomposition of the corresponding metal oleate salts in high-boiling solvents. Na-oleate was used as surfactant for shape control during the synthesis.

The synthesized particles are 20nm in size and appear core-shell like in bright field TEM images. High-resolution TEM (HRTEM) analysis reveals a FeO/MnO like structure in the core and a spinel like structure in the shell.

To resolve the spatial distribution and the oxidation state of the metals manganese and iron within the particles, high-resolution energy loss spectroscopy (EELS) and energy dispersive x-ray spectroscopy (EDS) were performed.

Iron and manganese show differences between their oxidation state in the core and the shell region of the particles. This is consistent with the structures observed in HRTEM analysis. The oxidation state of the iron ions is lower in the core than in the shell region. For manganese ions, only a thin surface layer shows different oxidation state. Traces of sodium used as surfactant during the synthesis were detected on the surface of the particles.