1, Sandia National Laboratories, Albuquerque, New Mexico, United States
Magnetic nanocomposites are a class of material that will allow for rational inductor design for power electronics. Zero-valent iron nanoparticles are a promising candidate as the magnetic fraction, due to the emergence of the superparamagnetic phenomenon at small sizes. Such superparamagnetic nanoparticles possess zero magnetic coercivity and are too small to support eddy currents, thereby removing two of the largest sources of energy loss in inductor applications.
We present the systematic growth of zero-valent iron nanoparticles with tight size and shape distribution via a reversible agglomeration method. We then demonstrate the scalability of this approach by synthesizing gram scale amounts of well-defined zero-valent iron nanoparticles. To ensure uniform switching and to prevent ferromagnetic domains from forming within the resulting nanocomposite the interparticle spacing of the nanoparticles must be closely controlled. To achieve this we have developed a ‘matrix-free’ approach in which a ligand exchange procedure is performed on the nanoparticles to express a chosen functionality at the surface. A cross-linking agent is then introduced to form a cross-linked network that reduces the organic fraction and maximizes particle loading.
The nanocomposite has good workability enabling it to be cast into custom molds, or directly 3D printed, leading to a number of different inductor form factors. Upon curing we obtain a mechanically strong, magnetically active material which shows promise for the next generation of inductors for power electronics.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.