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Magnetic nanoparticles for power absorption: Optimizing size, shape and magnetic properties |
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| Authors: | M.A. Gonzalez-Fernandez,M. André s-Vergé s,P. de la Presa,M.P. Morales,M.R. Ibarra,G.F. Goya |
| Affiliation: | a Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain b Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain c Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Spain d Departamento de Química Orgánica e Inorgánica, Universidad de Extremadura, Badajoz, Spain e Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Las Rozas, Madrid, Spain f Instituto de Ciencia de Materiales de Aragón, CSIC— Universidad de Zaragoza, Spain |
| Abstract: | We present a study on the magnetic properties of naked and silica-coated Fe3O4 nanoparticles with sizes between 5 and 110 nm. Their efficiency as heating agents was assessed through specific power absorption (SPA) measurements as a function of particle size and shape. The results show a strong dependence of the SPA with the particle size, with a maximum around 30 nm, as expected for a Néel relaxation mechanism in single-domain particles. The SiO2 shell thickness was found to play an important role in the SPA mechanism by hindering the heat outflow, thus decreasing the heating efficiency. It is concluded that a compromise between good heating efficiency and surface functionality for biomedical purposes can be attained by making the SiO2 functional coating as thin as possible. |
| Keywords: | 81.16.Be 81.07.&minus b 75.50.+a |
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