New ceramics for the informations storage: nanoparticles of titanium ferrites. Influence of oxidation and reduction reactions upon the coercivity

摘要

Nanocrystalline Fe-based spinels with composition fe_2.5Ti_90.5O_4 are obtained by two different routes : soft chemistry and high-energy ball milling. In the first case, two steps are involved : precipitation in an aqueous solution followed by thermal treatment of the powder under reducing atmosphere given by N_2/H_2H_2O mixtures. In the second case, the spinel phase is directly formed in the mill at room temperature by milling Fe+Fe_2O_3+TiO_2 in stoichiometric quantities under argon atmosphere.