Synthesis and mechanical/magnetic properties of nano-grained iron-oxides prepared with an inert gas condensation and pulse electric current sintering process

Nanocrystalline iron-oxide powder was fabricated with an inert gas condensation (IGC) method combined with evaporation, and in-situ oxidation techniques. The particle size of iron-oxide powder was controlled by varying the helium gas pressure between 0.1 and 10 Torr, with the smallest one =10 nm at 0.1 Torr. The nanostructure was characterized by TEM. Nanocrystalline iron-oxide powder was sintered with the pulse electric current sintering (PECS) method to obtain densified γ-Fe₂O₃ materials, and suitably densified nano-grained γ-Fe₂O₃ materials (≈ 40 nm) of great hardness were obtained. The correlation between the nanostructure and magnetic properties of nanocrystalline powder and densified γ-Fe₂O₃ materials was also investigated.