Particle size optimization of SrFe12O19 magnetic nanoparticles

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Particle size optimization of SrFe12O19 magnetic nanoparticles. J. Ahlburg,a M. S. Músquiza, C. Zeuthena, S. Kjeldgaarda, M. Stingaciua, M. Christensena aCenter for Materials Crystallography, Departement of Chemistry & iNano, Aarhus University, Denmark Since the invention of the electric motor, magnets have been a keystone in the electric era in which we live. Nowadays people carry around magnets in every small electronic device or gadget and magnets are being used as a diagnostic in medicine. [1] This puts a high demand on controlling the magnetic properties. Since the discovery of quantum mechanics magnetism have been described and measured on an atomic level, and the magnetic properties of bulk magnet can easily be measured, but what lies in between, the nanoscale region, have just recently been addressed. [2] Ferrites have shown great promise in the field of non-rare-earth metal magnets and the number of publications has grown exponentially for the last 50 years. [3] SrFe12O19 has excellent magnetic properties due to the high anisotropy of the unitcell and by making nanoparticles it is possible to have single magnetic domain particles. [4] This will greatly improve the energy product pr. Volume, which is needed in small devices. When nanoparticles of SrFe12O19 are formed the growth is furthermore such that platelets are formed making them easy to stack when forming a bulk magnet. In these studies we want to control the size and shape of the particles by using a simple setup suitable for rapid small scale testing of various synthesis conditions and teaching purposes. The setup allows changing temperature, pressure to adopted to near critical conditions of water.[5] The size and shape of the product can furthermore be controlled by varying the Sr:Fe ratio. X-ray powder diffraction is used to extract size and shape of the produced nanocrystallites. Furthermore it is demonstrated how it is possible to measure the magnetic properties using a very simple setup suitable for teaching purposes. To measure the magnetic properties the prepared nanocrystallites are compacted by cold pressing and sintered to increase the mechanical stability. [1] Sara A. Majetich et. al: Mrs bulletin, 38, 2013 [2] Weidenthaler C. Nanoscale,2011, 3, 792-810 [3] Pullar C. R. Progress in Materials Science 2012, 57, 1191–1334 [4] Fang, C. M.; Kools, F.; Metselaar, R.; de With, G.; de Groot, R. A. Journal of Physics: Condenced Matter 2003, 15, 6229–6237. [5] Drofenik, M.; Kristl, M.; Žnidaršic, A.; Hanžel, D.; Lisjak, D. Journal of the American Ceramic Society July 2007, 90, 2057–2061.
Original languageEnglish
Publication year2015
Publication statusPublished - 2015

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