Combinatorial Synthesis and Characterization of α''-Fe_xM_1‑xN₂ for Rare-Earth-Free Permanent Magnet Applications

The rapid pace of grid electrification increasingly relies on rare-earth permanent magnets, which are key components of motors that convert motion to electricity and vice versa. Current research seeks to develop permanent magnet materials that do not contain rare earth elements to circumvent global economic and environmental issues related to their industrial mining and production. Among rare-earth-free permanent magnets, metastable α''‑Fe₁₆N₂ has emerged as a leading candidate in this effort owing to its large magnetization (M_s) and elemental abundance. However, this material displays low coercivity and poor thermal stability, both of which require development ahead of deployment into commercial applications. DFT modeling has shown that the doping of α''-Fe₁₆N₂ with transition metals (α''-Fe_xM_1‑xN₂) may improve thermal stability and coercivity with minor reductions in M_s, however such behavior remains to be experimentally shown. In this presentation, combinatorial sputtering in tandem with spatially-resolved X-ray diffraction and wavelength-dispersive X-ray fluorescence is introduced as an experimental method to investigate the effects of transition metal doping on the phase stability and magnetic properties of α''‑Fe_xM_1‑xN₂.