ELECTRO-DISCHARGE METHOD TO MANUFACTURE SUPERPARAMAGNETIC IRON OXIDE NANOPARTICLES

摘要

Functional nanocrystalline metallic iron powder is produced by the method of electro-discharge in the low oxygen environment of water. In order to obtain superparamagnetic iron oxide Fe{sub}3O{sub}4, the manufacturing Fe particles were oxidized in the oxygen-rich water to continue oxidation process. Besides, the nanocrystalline Fe particle will be oxidized at temperatures of 200℃, 250℃, 300℃, 350℃, 400℃, 500℃ and 600℃ for 1 h in air to produce iron oxide α-Fe{sub}2O{sub}3. The X-ray diffraction, SEM and transmission electron microscope (TEM) were used to analyze the crystal structure and the powder morphologies. The results showed that pure Fe and FeO with a pretty narrow particle size distribution ranges from 1 nm to 10 nm were obtained by the method of electro-discharge. After oxygen-rich oxidation treatment the γ-Fe{sub}2O{sub}3 and Fe{sub}3O{sub}4 were obtained at room temperature in 10 days. Thereafter, no more transformation was found in water environment. This result proves that Fe{sub}3O{sub}4 can be a stable superparamagnetic iron oxide. However, for the Fe particles heat-treated at temperatures of 200 to 600℃, α-Fe{sub}2O{sub}3 was formed at temperatures above 300℃ for 1 h treating time. Further application studies of this material will be presented in our future research works.