Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 23: Micro- and Nanostructured Magnetic Materials

MA 23.10: Vortrag

Mittwoch, 2. April 2014, 12:00–12:15, HSZ 403

Field assisted sintering of nanostructured iron oxide composites — •Kerstin Witte, Wiktor Bodnar, and Eberhard Burkel — Institute of Physics, University of Rostock, August-Bebel-Str. 55, 18055 Rostock, Germany

The behaviour of magnetic materials depends strongly on their domain structure. For nanoparticles and thin films a broad range of interesting effects like superparamagnetism or giant magnetoresistance have been observed, while the behaviour of nanostructured bulk materials is still widely unknown. Various physical properties of bulk materials and composites can be significantly affected by the careful control of both composition and nanoscale grain structure. The rather novel field assisted sintering technique (FAST) is a promising tool for the consolidation and synthesis of such nanostructured bulk materials. During FAST a pulsed direct electric current and mechanical load are applied on precursor powder placed in a graphite die, leading to rapid heating of the densified powder. Advantages of FAST are short process times and the possibility of keeping nanostructured grains. To study changes in the behaviour of magnetic materials, soft magnetic iron oxides are an ideal system due to their metastability, as well as the large single domain size of magnetite and maghemite. In this study a stoichiometric mixture of hematite and iron was processed by FAST. The composition and other various physical properties of the obtained composites were determined using high energy X-ray diffraction, scanning electron microscopy and Mößbauer spectroscopy.