Ferromagnetism in Fe-doped tetra-needle like ZnO whiskers

The Fe-doped tetra-needle like ZnO whiskers (T-ZnOw) were prepared with different loadings of Fe3+ by a solid solution process. The structures and magnetic properties of the samples were characterized by using X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer, respectively. The results indicate that Fe3+ ions are successfully doped into the crystal lattice of T-ZnOw matrix. The second phase of ZnFe2O4 is formed by heavy doping of Fe3+ ions, and the solid solubility limit of Fe3+ in T-ZnOw crystal is about 0.7 mol%. The magnetic properties reveal that some of the Fe-doped T-ZnOw exhibits room-temperature ferromagnetic behaviors. The room-temperature ferromagnetism in the Fe-doped T-ZnOw system is ascribed to be originated from the change of the electronic states of ZnOw caused by irons doping.