Stoichiometry and orientation- and shape-mediated switching field enhancement of the heating properties of Fe3O4 circular banodiscs
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2021
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The generation of topological magnetic vortex-domain structures in iron-oxide nanomaterials has
promising applications in biomedical scenarios, such as heat generators for hyperthermia treatments.
In this report we describe alternative kinds of magnetic-vortex nanoparticles, circular Fe3O4 nanodiscs
(NDs), and dissect their heating properties by in-depth investigation of their shape and size, stoichiometry,
orientations, and switching field “HS” behaviors, through experiments and theoretical simulation. We find
that the stoichiometric NDs show better heating performance than nonstoichiometric materials because
of the significant electron hopping between Fe3+ and Fe2+ ion. The higher heating efficiency (in terms
of specific absorption rate, SAR) is observed only for the higher switching field regime, an effect that is
associated with the parallel and perpendicular alignment of nanodiscs with respect to low and high ac
magnetic field, respectively. A higher SAR of approximately 270 W/g is observed at a higher switching
field (approximately 700 Oe) for NDs of diameter 770 nm, which increases by a factor of 4 at a switching
field of approximately 360 Oe for NDs of diameter 200 nm. The reported results suggest that the heating
efficiency in these systems can be enhanced by controlling the switching field, which is, in turn, tuned by
size, shape, and orientation of circular magnetic vortex nanodiscs.
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NIRAULA, Gopal et al. Stoichiometry and orientation- and shape-mediated switching field enhancement of the heating properties of Fe3O4 circular nanodiscs. Physical Review Applied, College Park, v. 15, n. 1, e014056, 2021. DOI: 10.1103/PhysRevApplied.15.014056. Disponível em: https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.15.014056. Acesso em: 12 set. 2023.