Title :
Magnetic properties and microstructures of Fe3O4 -γFe2O3 intermediate state
Author :
Sato, M. ; Nakajima, G. ; Namikawa, T. ; Yamazaki, Y.
Author_Institution :
Tokyo Inst. of Technol., Yokohama, Japan
fDate :
9/1/1990 12:00:00 AM
Abstract :
Magnetic properties and microstructures of Fe3O4 -γFe2O3 intermediary films were studied to clarify the origin of the coercivity increase which occurs in the oxidation process of Fe3O4 to γFe2 O3. Fe3O4 films were prepared on quartz substrates by electron beam evaporation and were gradually oxidized in air at 240°C for 5 to 85 min. The maximum Hc of 1070 Oe was obtained at 50 min. The microstructure of the Fe3O4-γFe2O 3 intermediary films was directly investigated by high-resolution transmission electron microscopy (TEM). Specimens for the TEM observations were prepared by the ion thinning technique. The results indicate shrinkages in the films during the oxidation from 10 to 50 min. The results also show many dislocations, stacking faults, and lattice defects, suggesting that the stresses in the films correlate with the increase in Hc at the intermediate state
Keywords :
coercive force; crystal microstructure; dislocations; iron compounds; magnetic thin films; oxidation; stacking faults; transmission electron microscope examination of materials; vapour deposited coatings; 240 degC; Fe3O4-Fe2O3; TEM; coercivity; dislocations; electron beam evaporation; high-resolution transmission electron microscopy; intermediary films; ion thinning technique; lattice defects; microstructure; oxidation process; quartz substrates; stacking faults; Coercive force; Electron beams; Iron; Lattices; Magnetic films; Magnetic properties; Microstructure; Oxidation; Stacking; Transmission electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on
