High Pressure Synthesis of New Magnets, Featuring Diamagnetic Sources of Anisotropy
Permanent magnets are the functional component of electric motors and generators found in numerous renewable energy applications spanning from regenerative brakes to wind turbines. Magnets that generate higher magnetic flux per volume are central to improved energy generation in these applications. To develop a new class of permanent magnets while retaining the properties conferred by rare-earth elements, a fundamentally different approach is required. We hypothesize that by engendering a covalent interaction between two elements, it will be possible to interact the two components of a magnetic moment—spin and orbital angular momentum—from two separate atoms to form a complete magnetic moment. This seed project focuses on the scale up of the compound FeBi 2 , which was initially synthesized in our laboratory. Scale up approaches include slow decompression, alternate synthetic routes, and using fabrication approaches to more intimately mix the precursor elements. We also pursued the synthesis of new phases in the Mn-Bi system targeted to create new magnetic materials. In our initial experiments we decompressed FeBi 2 down to 2.9 GPa, demonstrating a kinetic stability to the phase that enabled it to be recovered to an order of magnitude lower pressure than that needed to synthesize it (30 GPa). Our goal is to recover this exciting material to ambient pressures so that we can isolate samples for detailed physical properties measurements. We have undertaken three distinct approaches toward that goal, which we summarize below. Our two most notable results are the formation of a quenchable phase through antimony doping of FeBi 2 , and the development of a new approach to preparing samples for diamond anvil cell syntheses.