Magnetic Materials for Green Technologies
Prof. Dr. Oliver Gutfleisch (FB Materialwissenschaft, Technische Universität Darmstadt, Darmstadt)

Due to their ubiquity, magnetic materials play an important role in improving the efficiency and performance of devices in electric power generation, conversion and transportation 1. Permanent magnets are essential components in motors and generators of hybrid and electric cars, wind turbines, etc. Magnetocaloric materials could be the basis for a new solid state energy efficient cooling technique alternative to compressor based refrigeration 2. Any improvements in magnetic materials will have a significant impact in these areas, on par with many “hot” energy materials (e.g. batteries, thermoelectrics, hydrogen storage, etc.).
The talk focuses on rare earth and rare earth free 3 permanent magnet and magnetocaloric materials with an emphasis on their optimization for energy and resource efficiency in terms of the usage of critical elements. The concept of criticality of strategic metals will be explained by looking at demand, sustainability and the reality of alternatives of rare earths. Synthesis, multiscale characterization and modelling, and property evaluation of the materials 4,5,6,7 will be examined considering their micromagnetic length scales and phase transition characteristics.
1 Magnetic Materials and Devices for the 21st Century: Stronger, Lighter, and More Energy Efficient, Adv. Mat. 23 (2011) 821.
2 Giant magnetocaloric effect driven by structural transition, Nature Mat. 11 (2012) 620.
3 Towards high-performance permanent magnets without rare earths, J. Phys.: Condens. Matter 26 (2014) 064205.
4 Preparation, characterization and modeling of ultra-high coercivity Sm-Co thin films. Adv. Electronics Mat. 1500009 (2015).
5 High energy density products in Battenberg structured magnets, Appl. Phys. Lett. 105 (2014) 19240.
6 Atomic Scale Features of Phase Boundaries in Hot Deformed Nd-Fe-Co-B-Ga Magnets Infiltrated with a Nd-Cu Eutectic Liquid, Acta Mat. 77 (2014) 111.
7 Large reversible magnetocaloric effect in Ni-Mn-In-Co, Appl. Phys. Lett. 106 (2015) 021901.