Gram-Scale Synthesis of Fe₃N Nanoparticles via a One-Pot Thermal Decomposition Route: Implications for Magnetic Fluid Hyperthermia Applications

ε-Fe3N nanoparticles were produced in gram-scale quantities using a one-pot thermal decomposition route, yielding monodisperse particles with an average diameter of 13.5 nm. We thoroughly investigated the structure, surface chemistry, size distribution, and magnetism using in situ high-temperature X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution TEM, Mössbauer spectroscopy, dynamic light scattering, AC magnetometry, and temperature-dependent magnetometry. The room-temperature saturation magnetization of 128 A·m2/kg significantly exceeds that of conventionally used iron oxides and results in an impressive heating performance reaching a specific absorption rate of several kW/g with 508 W/g within biological safety limits which are the highest values reported to-date for iron nitride nanoparticles. The measured magnetocrystalline anisotropy constant of 133.9 kJ/m3 is in very good agreement with density functional theory calculations demonstrating the quality and convergence of the experimental and theoretical results. This work positions ε-Fe3N nanoparticles as a potential sustainable material without critical or toxic elements for magnetic fluid hyperthermia and other applications that would benefit from much increased magnetization.