Optimization of the magnetic properties of aligned Co nanowires/polymer composites for the fabrication of permanent magnets

Weiqing Fang (1) , Ioannis Panagiotopoulos (1) , Frédéric Ott (1) , François Boué (1) , Ait-Atmane Kahina (2) , Jean-Yves Piquemal (2) , G. Viau (3) , Florent Dalmas (4)

1 LLB - UMR 12 - Laboratoire Léon Brillouin
2 ITODYS (UMR_7086) - Interfaces, Traitements, Organisation et Dynamique des Systèmes
3 LPCNO - Laboratoire de physique et chimie des nano-objets
4 ICMPE - Institut de Chimie et des Matériaux Paris-Est

We aim at combining high coercivity magnetic nanowires in a polymer matrix in a view to fabricate rare-­‐earth free bonded magnets. In particular, our aim is to fabricate anisotropic materials by aligning the wires in the polymer matrix. We have explored the different parameters of the fabrication process in order to produce a material with the best possible magnetic properties. We show that the choice of a proper solvent allows obtaining stable nanowire suspensions. The length and the type of the polymer chains play also an important role. Smaller chains (M w <10000) provide better magnetization results. The magnetic field applied during the casting of the material plays also a role and should be of the order of a fraction of a tesla. The local order of the nanowires in the matrix has been characterized by TEM and Small Angle Neutron Scattering. The correlation between the local order of the wires and the magnetic properties is discussed. Materials with coercivity µ 0 H c up to 0.70 T at room temperature have been obtained.

Mots clés: polymer; nanocomposites; magnetic nanoparticles; nanorods; alignment; magnets; coercivity; magnetisation

Domaines: Polymères; Science des matériaux [cond-mat.mtrl-sci]; Matière Molle [cond-mat.soft]; Micro et nanotechnologies/Microélectronique; Génie des procédés

Weiqing Fang, Ioannis Panagiotopoulos, Frédéric Ott, François Boué, Ait-Atmane Kahina, et al.. Optimization of the magnetic properties of aligned Co nanowires/polymer composites for the fabrication of permanent magnets. Journal of Nanoparticle Research, 2014, 16, pp.2265. ⟨10.1007/s11051-014-2265-x⟩. ⟨hal-01396790⟩