Berlin 2024 – scientific programme
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MA: Fachverband Magnetismus
MA 7: Bulk Magnetic Materials and Magnetic Particles/Clusters
MA 7.6: Talk
Monday, March 18, 2024, 10:45–11:00, EB 407
Shape-dependent magnetic study of hematite nanospindles — •Juri Kopp1, Joachim Landers1, Soma Salamon1, Gerald Richwien2, Benoît Rhein2, Annette Schmidt2, and Heiko Wende1 — 1Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen — 2Institute for Physical Chemistry, University of Cologne
Hematite nanospindles can be synthesized relatively easily in various aspect ratios and can be incorporated in aqueous solutions. When considering hematite-based ferrofluids, the question arises to what extent the degree of particle elongation influences the orientation behavior and mobility of nanospindles. For this purpose, hematite nanospindles with different aspect ratios in a 70 wt% glycerol-water mixture were investigated by magnetic field dependent Mössbauer spectroscopy, as well as magnetometry. As expected, the field-dependent Mössbauer experiments showed that the more elongated particles (aspect ratio of 3.7 and 5.2) were easier to align in the field due to the greater magnetic moment compared to the sample with a ratio of 2.5. Surprisingly the reference powder measurements for the sample with the aspect ratio of 1.0 showed a relatively sharp Morin-transition, in contrast to the rest of the other samples of higher aspect ratio, where no such transition occurred over the entire temperature range. Based on these results, we aim for the incorporation of the nanospindles into liquid crystalline matrices and to investigate anisotropic diffusion in ferronematic phases. We gratefully acknowledge funding by the DFG through LA5175/1-1.
Keywords: Hematite nanospindles; Mössbauer spectroscopy; Ferrofluid