Fe16N2 nanoparticles for the design of permanent magnet. – FENMAG

The project "FENMAG" relates to the current need to develop new nanomaterials for the production of permanent magnets of high power and with a reduced ecological footprint throughout their life cycle.
The issue of permanent magnets has become strategic again this last decade. Magnets are made up of magnetic materials called "hard", that is to say with strong spontaneous magnetization and strong anisotropy, capable of storing strong magnetic energies per unit of mass and volume, and thus reducing the quantities of necessary materials for the intended applications. To date, medium and high performance magnets require rare earth-based materials such as SmCo or NdFeB. The latter must be doped with dysprosium at prohibitive cost to maintain their performance level up to 100-150 ° C. With the development of electrification systems, the production of electricity from renewable energies (wind, maritime), hybrid vehicles, the need in terms of volume is growing very rapidly. Military applications, with the increase in on-board electrical power, the increase in the number of electrically controlled components do not escape this trend. However, rare earth resources are limited, expensive and have become a virtual monopoly of China. To reduce this dependency, it is necessary to produce new magnetic phases with increased performances, and to implement alternatives to the use of rare earths.
To meet this fundamental need, the FENMAG project aims to produce iron-nitride magnetic single-domain nanoparticles (a '' - Fe16N2 phase) that could be integrated as new bricks in permanent magnets. The targeted phase a '' - Fe16N2 has serious advantages in view of the desired properties:
- a spontaneous magnetization superior to that of massive Fe.
- the strongest anisotropy for a material not comprising heavy metal, noble metal or rare earth.
- the absence of a risk of diffuse pollution in the event of dissemination, and of non-recycling.
- the lowest cost in terms of the elements that compose it.
- a theoretical stored energy potential of 135 MGOe, superior to the best materials doped with rare earths (60 MGOe)
To carry out this ambitious project, FENMAG associates 3 Toulouse laboratories that have complementary expertise in nanomaterials science: the LCC for the chemical synthesis of perfectly calibrated metallic and magnetic nanoparticles, the CEMES for the study of the chemical and structural order and the SPS (spark plasma sintering) sintering processes, and the LPCNO for the study of the magnetic properties of nanoparticles. The objectives of the project are:
- to develop a new, unambiguous and reproducible chemical synthesis pathway of nanoparticles models of iron nitride '' - Fe16N2 (composition, chemical and atomic order controlled)
- Shape these nanoparticles to make a small magnet based on iron nitride a '' - Fe16N2 (mass 1g).
- Qualify this phase for the manufacture of magnets, potentially in the intermediate zone between rare earth magnets and ferrites.
- lay the groundwork for a scale-up of the production of these nanoparticles and facilitate the production of small magnets.
The process will involve a SME company for the scale-up phase.