Highly dispersive α″-Fe₁₆N₂ particle synthesis using hydroxyapatite coating

Alpha″-Fe₁₆N₂ nanoparticles (NPs) with high magnetic crystalline anisotropy are useful for practical applications such as recording media. However, due to their strongly aggregated and/or sintered form, which occurs during synthesis, the utilization of the NPs has been limited thus far. Here, we report a method for synthesizing highly dispersive α″-Fe₁₆N₂ NPs using hydroxyapatite (HAp). The chemically and thermally stable structure of the HAp coating results in the isolation of individual NPs, such that sintering is prevented during synthesis. Additionally, the acicular shape of the HAp crystal did not hinder gas diffusion during the gas reaction. Finally, HAp can be removed by a chelating agent without deteriorating the magnetic properties, resulting in highly dispersive α″-Fe₁₆N₂ NPs. - Graphical abstract: Synthesis process of highly dispersive α″-Fe₁₆N₂ particles using hydroxyapatite coating and SEM images of nanoparticles. - Highlights: • Highly dispersed α″-Fe₁₆N₂ NPs were synthesized using hydroxyapatite (HAp). • HAp coating was stable chemically and thermally during gas reaction of α″-Fe₁₆N₂ synthesis. • The magnetic property of the resultant Fe₁₆N₂ NPs are M_s of 170 emu/g and H_C of 2450 Oe