Synthesis of carbon coated iron nitride nanoparticles by using microwave plasma technique

Abstract Carbon-coated iron nitride nanoparticles were synthesized using ferrocene as the precursor material with an in-house manufactured microwave-plasma reaction system. XRD revealed that the nanoparticles contained mixed phases of iron nitride (FeN_0.0589 and ε-Fe₃N) and α-Fe. In the case of TEM, the powder displayed a core–shell structure with a core diameter of ∼15 nm and had a multilayer carbon structure. The particle sizes in all samples were 10–80 nm. The Raman spectra of the nanoparticles justified that the multilayer carbon coatings had an amorphous graphitic structure. The nanoparticles developed at an N₂ flow rate of 10 slpm yielded a superior Ms value of 37.2 emu g⁻¹. An increase in the N₂ flow rate exhibited a significant influence on the plasma temperature and reaction time, thereby affecting the composition of the mixed phase, the shape and size of the particles, and the uniformity and thickness of the carbon coating. This study provided a simple, efficient and economical method to prepare iron nitride magnetic nanoparticles, which is expected to be widely applied in industrial mass production.