Influence of the hierarchical architecture of multi-core iron oxide nanoflowers on their magnetic properties

  • Autor:

    Neumann, S. / Kuger, L. / Arlt, C.-R. / Franzreb, M./ Rafaja, D. (2023)

  • Quelle:

    Scientific Reports, 2023,13:5673

  • Datum: April 2023
  • Abstract

    Magnetic properties of superparamagnetic iron oxide nanoparticles are controlled mainly by their
    particle size and by their particle size distribution. Magnetic properties of multi‑core iron oxide
    nanoparticles, often called iron oxide nanoflowers (IONFs), are additionally affected by the interaction
    of magnetic moments between neighboring cores. The knowledge about the hierarchical structure of
    IONFs is therefore essential for understanding the magnetic properties of IONFs. In this contribution,
    the architecture of multi‑core IONFs was investigated using correlative multiscale transmission
    electron microscopy (TEM), X‑ray diffraction and dynamic light scattering. The multiscale TEM
    measurements comprised low‑resolution and high‑resolution imaging as well as geometric phase
    analysis. The IONFs contained maghemite with the average chemical composition γ‑Fe2.72±0.02O4 . The
    metallic vacancies located on the octahedral lattice sites of the spinel ferrite structure were partially
    ordered. Individual IONFs consisted of several cores showing frequently a specific crystallographic
    orientation relationship between direct neighbors. This oriented attachment may facilitate
    the magnetic alignment within the cores. Individual cores were composed of partially coherent
    nanocrystals having almost the same crystallographic orientation. The sizes of individual constituents
    revealed by the microstructure analysis were correlated with the magnetic particle sizes that were
    obtained from fitting the measured magnetization curve by the Langevin function.