phD thesis 2025 – 2028
Fe-based nanorods for the fabrication of « green »magnets

Supervisors :

Magnetic materials play a major role in the currentenergy and societal transitions. However,the development of sustainable yet performant materials, without critical elements such asrare-earths (RE), remains a challenge [1,2]. This thesis is part of a large project involving 5laboratories with complementary expertise in chemistry, physics, chemical engineering,artificial intelligence and data science, to develop iron-based nanorods (NRs) with optimizedmagnetic properties. Thereal scientific challengeconsists in breaking thesymmetry of the Fecrystalline structure whilekeeping an optimized aspectratio. Such control will allowachieving magnet-likeproperties in assemblies.The LPCNO has a strong expertise on the developmentof rare-earth-free

Figure 1. a) Schematic view of the « bottom-up » approach. b)Transmission electron microscopy image of Co NRs synthesized byseed-mediated growth.

The LPCNO has a strong expertise on the developmentof rare-earth-free magnets using adirected assembly approach of elementary building blocks (Fig 1a). To date, this work has beencarried out on Co nanorods (NRs), synthesized by seeded growth (Fig 1b), and has led to high-performance integrated magnets [3,4]. The CEA-LIONSis known, among others, forsucceeding in breaking the symmetry of Au, leadingto the synthesis and characterization ofAu nanorods using the seeded growth method [5,6]. At the crossroad between these twolaboratories, the aim of this PhD will be to transpose the seeded growth method on Fe NRs.An exploration of the range of parameters (nature of seeds, growth conditions, ligandconcentration) will be undertaken using conventional synthesis and microfluidic chips. Theparticles at the different stage of the reaction will be characterized by X-ray scattering (SAXS,WAXS), electron microscopy (TEM and SEM), diffraction (XRD) and magnetometry (VSM).Eventually, in-situ SAXS and WAXS experiments willbe performed combining the microfluidicchip, synchrotron radiation and AI models to determine the optimized synthesis parameters.The work will be mainly conducting at LPCNO, Toulouse with short stay visit at CEA-Lions inorder to perform SAXS/WAXS experiments. The candidate will work in close collaboration withthe two other PhD students involved in the projectand working on the AI models and on thefabrication of the microfluidic chip.

[1] Silveyra, J. M. et al. Soft Magnetic Materials for a Sustainable and Electrified World.Science 2018,362, eaao0195. [2]Gutfleisch, O.et al. Magnetic Materials and Devicesfor the 21st Century: Stronger, Lighter, and More Energy Efficient.Adv. Mater.2011,23, 821. [3] Ramamoorthy, R. K. et al. One-Pot Seed-Mediated Growth of Co Nanoparticles by the Polyol Process: Unravelingthe Heterogeneous Nucleation.Nano Lett.2019,19, 9160. [4] Moritz, P.et al.. « Procédé de Fabrication d’un Aimant Permanent Ou Doux ». PCT/FR2019/053046. [5] Hubert, F. et al. Growth andovergrowth of concentrated gold nanorods: time resolved SAXS and XANES. Crystal growth & design 2012, 12(3), 1548. [6]Canbek Ozdil, Z. C. et al Competitive Seeded Growth: An Original Toolto Investigate Anisotropic Gold Nanoparticle GrowthMechanism. J. Phys. Chem. C 2019, 123(41), 25320.