Magnetostructural study of iron–dextran

Abstract Dynamic AC magnetic susceptibility, magnetisation and electron microscopy analyses have been performed on several samples derived from a commercial iron–dextran complex. The system contains nanometric spindle shape nanoparticles whose electron diffraction pattern corresponds to that of the iron oxyhydroxide akaganeite (β-FeOOH) and whose magnetic behaviour is superparamagnetic above approximately 100 K. Below such temperature the system exhibits outstanding magnetic relaxation, associated to the blocking of the magnetic moments which result from the incomplete compensation of the intraparticle antiferromagnetic spins. This phenomenon, which is clearly manifested in the temperature dependent out-of-phase susceptibility χ ″( T ) profile, does not fit the Arrhenius relaxation model and seems not to depend on the type of sample processing, in particular on the degree of particle dilution.