Study of the role of the ligands coordinated at the surface of pure Wüstite nanoparticles prepared following a room temperature organometallic method: Evidence of ferromagnetic – in shell- and antiferromagnetic – in core magnetic behaviors

• Published in: Materials chemistry and physics 2011-09, Vol.129 (1), p.605-610
• Main Authors: Glaria, Arnaud, Kahn, Myrtil L., Chaudret, Bruno, Lecante, Pierre, Casanove, Marie-José, Barbara, Bernard
• Format: Article
• Language: English
• Subjects: Condensed Matter; Magnetism; Materials Science; Nanoparticles; Organometallic chemistry; Physics; Wüstite
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2011.04.077

► Pure Wüstite (Fe 1− y O) nanoparticles synthesized by organometallic chemistry. ► The influence of the surface ligands on the magnetic properties. ► Ferromagnetic core–antiferromagnetic shell magnetic nanoparticles. Wüstite particles (Fe 1− y O) are synthesized using controlled hydrolysis at room temperature of [Fe(N(SiMe 3) 2) 2] and stabilized by amine ligands. This method leads to 5 nm pure wüstite particles. This phase is clearly identified by transmission electron microscopy and wide angle X-ray scattering. Distortion in the crystallographic structure has been demonstrated. Particular attention is paid on the Fe(III) formation. Moreover, a combination of Mössbauer spectroscopy and SQuID measurements, revealed that the particles are composed of an antiferromagnetic core surrounded by a ferromagnetic shell. According to the Néel theory, the Fe(III) and Fe(II) ions present in the particles are ferromagnetically coupled and the proportion of Fe(III) ions varies from 3.9 to 7.1% as a function of the amine ligand.