Synthesis of Nano-Crystalline Magnetite by SHS Route

Nano-crystalline magnetite powder has been prepared successfully by self- propagating high-temperature synthesis (SHS) reaction using Fe, Fe₂O₃ and sodium perchlorate as starting materials. The synthesized powder has been subjected to intense milling using a planetary ball mill up to 10 h. The effects of Fe/Fe₂O₃ molar ratio as well as the milling time on the powder particle characteristics were investigated using XRD, SEM, TEM and VSM techniques. XRD results showed that the non-stoichiometric molar ratio (2.5 Fe+0.5 Fe₂O₃) is more favorable to synthesize magnetite phase. The phase composition was not affected significantly by milling process while both mean particle and crystallite size were decreased. Mean crystallite size of magnetite reduced from 90 to 40 nm after 10 h milling. Saturation magnetization (M_s) increased from 47.6 in non-milled sample to 69.6 emu/g in milled sample for 10 h, while the coercivity (H_c) reduced from 365 to 120 Oe after milling.