J. Phys. IV France 07 (1997) C1-599-C1-600
Dark Field Observation of Fe3O4-γFe2O3 Multiphase FilmsY. Yamazaki1, T. Namikawa1, Y. Koizumi2 and S. Meguro2
1 Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226, Japan
2 Tokai University, Kitakaname, Hiratsuka-shi 259-12, Japan
We investigated the phase separation of cubic and tetragonal systems in Fe3O4-γFe2O3 intermediate thin films. An Fe thin film of 50 nm was deposited on a SiO2 substrate using an electron beam evaporator at room temperature. The film was oxidized to αFe2O3 at 400°C in air, then the film was reduced to Fe3O4 at 320°C in methanol vapor. The gradual oxidation of the Fe3O4 film to γFe2O3 film at 240°C was terminated when the coercive force of the film increased more than 1000 Oe at an intermediate state. The intermediate film was examined by dark-field TEM observation with tetragonal diffraction spots. The result revealed that crystallites of about 10 nm of tetragonal structure are distributed in a matrix of cubic phase.
© EDP Sciences 1997