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.
The talk focuses on rare earth and rare earth free permanent magnets 3 and magnetocaloric materials, with an emphasis on their optimization for energy and resource efficiency in terms critical element utilization. The concept of criticality of strategic metals is explained by looking at demand, sustainability 4 and the reality of alternatives of rare earths. Modelling, synthesis, characterization, and property evaluation of the materials will be discussed considering their micromagnetic length scales, hysteresis and phase transition characteristics.
Specifically I will give examples for how to (a) reduce Dy needs by grain boundary diffusion processes, (b) utilize excess Ce in (Nd,Ce)Fe14B balance magnets, (c) tailor anisotropy by 5d elements in (Fe1−xCox)2B alloys and (d) assess magnetic moments in iron nitrides 5-7.
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.
4Recycling Used Nd-Fe-B Sintered Magnets via a Hydrogen-Based Route to Produce Anisotropic, Resin Bonded Magnets, Advanced Energy Materials 3 (2013) 151.
5Temperature dependent Dy diffusion processes in Nd-Fe-B permanent magnets, Acta Mat. 83 (2015) 248
6Effect of doping by 5d elements on magnetic properties of (Fe1−xCox)2B alloys, Phys. Rev. B 92 (2015) 174413.
7Increased magnetic moment induced by lattice expansion from α-Fe to α′-Fe8N, J. Appl. Phys. 117 (2015) 173911.
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