Abstract
The Ni2+-substituting magnetite formation in the wet process in a high magnetic field from 0 to 8 T generated with a 10 T cryocooler-cooled superconducting magnet has been studied at iron ions concentration of 1500 mg/l at Fe2+/Fe3+(Rf) mole ratio of 1/2 and 2/1. The particle size (nanoparticles) of Ni2+-substituting magnetite was decreased with increasing magnetic field. Also, the magnetic field enhanced the reaction rate of ferrite formation. The Ni2+ content of Ni2+-substituting magnetite at Rf= 2/1 was lower than that at Rf=1/2. In the Ni2+-substituting magnetite, the lattice parameter decreases with an increase of magnetic field from 0 to 8 T, indicating that high magnetic fields enhance a formation of Ni2+-substituting magnetite (enhancement of solubility of Ni2+ into magnetite). This result is supported by the experimental result which the magnetite formed in a high magnetic field tends to adsorb Ni2+ in the reaction solution in a high magnetic field, indicating that a high magnetic field enhances the higher incorporation of Ni2+ into spinel structure.
