Structure and ferromagnetism of Fe-doped and Fe-and Co-codoped ZnO nanoparticles synthesized by homogeneous precipitation method

ZnO, Zn _0.90Fe _0.10O and Zn _0.90Fe _0.08Co _0.02O nanoparticles have been successfully prepared by the homogeneous precipitation method in an open system at room temperature. The structures and magnetic properties of the samples have been characterized by X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry. The X-ray diffraction result demonstrates a hexagonal wurtzite structure and a secondary phase of spinel in doped ZnO. The scanning electron microscope image of Zn _0.90Fe _0.10O reveals an average particle size of 40 nm with uniform shape, while the Zn _0.90Fe _0.08Co _0.02O nanoparticles present an uneven size range from 20 nm to 60 nm. Magnetic measurement indicates that Fe doping can induce weak room temperature ferromagnetism, and the coercivity was enhanced up to 762 Oe with strikingly magnetic saturation when co-doped with Co.