Advanced Sustainable Permanent Magnets

The discovery of rare-earth-based permanent magnets revolutionized modern technology, enabling advances in renewable energy, medical applications, defense, and consumer electronics. Since the 1960s, rare-earth-transition metal alloys, such as SmCo and NdFeB, have demonstrated exceptional magnetic properties, with NdFeB magnets now dominating the market due to their superior energy product ((BH)max > 440 kJ·m-3) and high coercivity (> 2 T). However, the reliance on critical raw materials, such as rare earth elements (REs) and cobalt, poses significant environmental and geopolitical challenges. The extraction and refinement of these materials are complex, energy-intensive, and generate hazardous waste. To address these concerns, research efforts have focused on alternative hard magnetic materials, including Fe-rich phases, Mn-based alloys and ThMn12-type compounds, which reduce RE content while maintaining competitive magnetic performance. Despite advancements, these alternatives still have to improve the performance of NdFeB magnets. The growing demand for permanent magnets in wind energy and electric vehicles underscores the urgent need for sustainable, high-performance materials. This chapter explores the historical development, material properties, and future perspectives of permanent magnets, emphasizing strategies to mitigate supply chain