Towards nano-based ceramic permanent magnets

Hard ferrite-based magnets are the most produced type of permanent magnets (PMs) in the world and, after rare – earth PMs, the second market in terms of sales. The recent crisis of the rare earths, that gives rise to the criticality in the production of rare-earth PMs, and the strong request of PM for Green Transition technologies like wind generators and electric mobility have gave rise to an increasing interest in the improvement of the magnetic performances of the ceramic PMs. The main aim is to increase their energy product (>30 kJm-3), the remanence induction (>0,4 T) but also their greener production. In this presentation, I will illustrate different research lines covering these challenges considering the use of novel nanomaterials. I will show that nanoparticles exhibit better magnetic properties (mainly high coercive field) that conventional micrometric powders, reaching the theoretic limit of the performances. I will discuss also on alternative materials like doped M-type ferrites and hybrid ferrite-metal nanomaterials. Finally, I will illustrate different specific methods to produce ceramic PMs using nanomaterials