Alignment under Magnetic Field of Mixed Fe <inf>2</inf> O <inf>3</inf> /SiO <inf>2</inf> Colloidal Mesoporous Particles Induced by Shape Anisotropy

Jheng Guang Li, Giulia Fornasieri, Anne Bleuzen, Martí Gich, Alexandre Gloter, Frédéric Bouquet, Marianne Impéror-Clerc

    Research output: Contribution to journalArticleResearchpeer-review

    13 Citations (Scopus)

    Abstract

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim When using the bottom-up approach with anisotropic building-blocks, an important goal is to find simple methods to elaborate nanocomposite materials with a truly macroscopic anisotropy. Here, micrometer size colloidal mesoporous particles with a highly anisotropic rod-like shape (aspect ratio ≈ 10) have been fabricated from silica (SiO 2 ) and iron oxide (Fe 2 O 3 ). When dispersed in a solvent, these particles can be easily oriented using a magnetic field (≈200 mT). A macroscopic orientation of the particles is achieved, with their long axis parallel to the field, due to the shape anisotropy of the magnetic component of the particles. The iron oxide nanocrystals are confined inside the porosity and they form columns in the nanochannels. Two different polymorphs of Fe 2 O 3 iron oxide have been stabilized, the superparamagnetic γ-phase and the rarest multiferroic ε-phase. The phase transformation between these two polymorphs occurs around 900 °C. Because growth occurs under confinement, a preferred crystallographic orientation of iron oxide is obtained, and structural relationships between the two polymorphs are revealed. These findings open completely new possibilities for the design of macroscopically oriented mesoporous nanocomposites, using such strongly anisotropic Fe 2 O 3 /silica particles. Moreover, in the case of the ε-phase, nanocomposites with original anisotropic magnetic properties are in view.
    Original languageEnglish
    Pages (from-to)5981-5988
    JournalSmall
    Volume12
    Issue number43
    DOIs
    Publication statusPublished - 16 Nov 2016

    Keywords

    • iron oxide
    • magnetic particles
    • mesoporous materials
    • nanocomposites
    • shape anisotropy

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