ZnFe2O4 Nanotubes: Microstructure and Magnetic Properties

Employing an electron energy-loss spectrum (EELS), we have found that the structure of ZnFe2O4 nanotubes deviated from the normal spinel structure as the calcination temperature decreases. More Fe3+ ions migrate to the tetrahedral sites (A sites) rather than staying in their equilibrium octahedral sites (B sites). This results in the enhanced superexchange interactions between Fe3+ ions, thus affecting the magnetic properties of the nanotubes, i.e., higher blocking temperature (TB) and larger saturation magnetization (MS), etc. On the other hand, we have also found that deviation of the Fe/Zn from 2 affects the magnetic properties of the nanotube samples. This should be caused by the enhanced superexchange interactions resulting from the extra Fe3+ ions in the nonstoichiometric sample.