A high magnetic field effect on the M(II)-substituted magnetite formation (M=Ni, Mn, Co) in the wet process

Abstract

The M(II)-substituted magnetite (M=Ni, Co and Mn) formation in the wet process in a high magnetic field from 0 to 8 T generated by a superconducting magnet has been studied at the iron ion concentration of 1500 mg/l and the Fe(II)/Fe(III) mole ratios ( R f) of 1 2 and 2 1 . The particle size of the M(II)-substituted magnetite was about 12 nm at R f = 2 1 and about 7 nm at R f = 1 2 . The Ni(II) content of the Ni(II)-substituted magnetite at R f = 2 1 was lower than that at R f= 1 2 . In the Ni(II)-substituted magnetite, the lattice parameter increases with an increase in the magnetic field from 0 to 8 T, indicating that high magnetic fields enhance the formation of the Ni(II)-substituted magnetite (solubility enhancement of Ni(II) to magnetite). Also, the lattice parameter of the Co(II)-substituted magnetite decreased with the increasing magnetic field, however, an increase in the lattice parameter was not found in the Mn(II)-substituted magnetite. The presence of large amounts of vacancies was found in the Ni(II)-substituted magnetite formed in high magnetic fields by XRD and atomic absorption analysis. This result is supported by the experimental result in which the magnetite formed in a high magnetic field tends to adsorb Ni(II) in a high magnetic field, and results in the higher incorporation of Ni(II) into the spinel structure.