From Mn 3 O 4 /MnO core–shell nanoparticles to hollow MnO: evolution of magnetic propertiesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 10 августа 2018 г.
Аннотация:Manganese oxide nanoparticles (MNOPs), when dispersed in a water solution, show a magnetic behavior that drastically changes after an aging process. In this paper, the variation in the magnetic properties has been correlated with the structural evolution of the nanoparticles: in particular, the as prepared Mn 3 O 4 /MnO core/shell system manifests a low temperature magnetization reversal that is strongly affected by the presence of the MnO shell and, in particular, by the existence of a frustrated interfacial region playing a key role in determining the low temperature irreversibility, the finite coercivity slightly above the Curie temperature of the Mn 3 O 4 phase and the horizontal displacement of the FC-hysteresis loop. On the other hand, the magnetic behavior of the aged system results dominated by the presence of Mn 3 O 4 whose highly anisotropic character (i.e. high coercivity and high magnetization remanence) is attributed to the presence of a large fraction of surface spins. Such a result is consistent with the structural evolution, from core/shell to hollow nanoparticles, as shown by TEM observation.