THE MAGNETIC DISACCOMMODATION IN TITANIUM-DOPED MAGNETITE

The domain wall stabilization processes in titanium doped magnetite is investigated by means of disaccommodation techniques. The time evolut ion of the initial magnetic susceptibility after sample demagnetizatio n is measured in temperature range 80 to 500 K for polycrystalline spe cimens with nominal composition, Fe3-xTixO4, (0<x<0.1). The presence o f Ti4+ ions in the spinel lattice changes drastically the disaccommoda tion 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) i nto (IV', IV, III) at temperatures close to 215 K, 260 K and 300 K res pectively. Furthermore, a new long-range diffusion contribution appear s in temperature region II, whereas peak I increases its relative cont ribution. The origin of the observed phenomena is discussed in terms o f 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' ).