J. Phys. IV France 07 (1997) C1-605-C1-606
The Magnetic Disaccommodation in Titanium Doped MagnetiteK. Bendimya, C. de Francisco, P. Hernandez, O. Alejos and J.M. Muñoz
Dpto. Electricidad y Electronica, Facultad de Ciencias, Universidad de Valladolid, 47071 Valladolid, Spain
The domain wall stabilization processes in titanium doped magnetite is investigated by means of disaccommodation techniques. The time evolution of the initial magnetic susceptibility after sample demagnetization is measured in temperature range 80 to 500 K for polycrystalline specimens with nominal composition, Fe3-xTixO4, (0<x<0.1). The presence of Ti4+ ions in the spinel lattice changes drastically the disaccommodation spectra observed in vacancy-doped magnetite. The increase of the tetravalent cations in the lattice involves an almost linear decrease of the Verwey temperature and the splitting of processes III (300 K) into (IV', IV, III) at temperatures close to 215 K, 260 K and 300 K respectively. Furthermore, a new long-range diffusion contribution appears in temperature region II, whereas peak I increases its relative contribution. The origin of the observed phenomena is discussed in terms of Fe2+ ions jumps into the vacancies as in Fe3O4 (process III), jumps of Fe2+ into a vacancies in octants with a Ti4+ (process IV) and jumps of Fe2+ which lies on octants with a Ti4+ into vacancies (process IV').
© EDP Sciences 1997