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Issue 16, 2017
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The internal structure of magnetic nanoparticles determines the magnetic response

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Abstract

This work aims to emphasize that the magnetic response of single-domain magnetic nanoparticles (NPs) is driven by the NPs’ internal structure, and the NP size dependencies of magnetic properties are overestimated. The relationship between the degree of the NPs’ crystallinity and magnetic response is unambiguously demonstrated in eight samples of uniform maghemite/magnetite NPs and corroborated with the results obtained for about 20 samples of spinel ferrite NPs with different degrees of crystallinity. The NP samples were prepared by the thermal decomposition of an organic iron precursor subjected to varying reaction conditions, yielding variations in the NP size, shape and relative crystallinity. We characterized the samples by using several complementary methods, such as powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), high resolution TEM (HR-TEM) and Mössbauer spectroscopy (MS). We evaluated the NPs’ relative crystallinity by comparing the NP sizes determined from TEM and PXRD and further inspecting the NPs’ internal structure and relative crystallinity by using HR-TEM. The results of the structural characterization were put in the context of the NPs’ magnetic response. In this work, the highest saturation magnetization (Ms) was measured for the smallest but well-crystalline NPs, while the larger NPs exhibiting worse crystallinity revealed a lower Ms. Our results clearly demonstrate that the NP crystallinity level that is mirrored in the internal spin order drives the specific magnetic response of the single-domain NPs.

Graphical abstract: The internal structure of magnetic nanoparticles determines the magnetic response

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Publication details

The article was received on 13 Sep 2016, accepted on 13 Mar 2017 and first published on 16 Mar 2017


Article type: Paper
DOI: 10.1039/C6NR07262C
Citation: Nanoscale, 2017,9, 5129-5140
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    The internal structure of magnetic nanoparticles determines the magnetic response

    B. Pacakova, S. Kubickova, G. Salas, A. R. Mantlikova, M. Marciello, M. P. Morales, D. Niznansky and J. Vejpravova, Nanoscale, 2017, 9, 5129
    DOI: 10.1039/C6NR07262C

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