MAGNETIC IRON OXIDE NANOPOWDER AND PROCESS FOR PRODUCING SAME

摘要

Provided are: a magnetic iron oxide nanopowder which is constituted of ε-Fe2O3 having an aspect ratio of 1.2 or higher and has an average major-axis length of 20 nm or less; and a process for producing the magnetic iron oxide nanopowder. Nanoparticles of β-FeO(OH) are coated with silicon oxide. The β-FeO(OH) nanoparticles coated with silicon oxide are then heat-treated in an oxidizing atmosphere to obtain a heat-treated powder. An aqueous alkali solution is added to the heat-treated powder to remove the silicon oxide therefrom. Sediments are removed from the resultant mixture to obtain a magnetic iron oxide nanopowder.