Synthesis, structure and ferromagnetic properties of Ni-doped ZnO nanoparticles

Nanosized Ni-doped ZnO particles were synthesized by rheological phase reaction-precursor method and the thermal decomposition of oxalate precursors was studied by thermogravimetry and differential thermal analysis in air atmosphere. X-ray analysis reveals that the Ni-doped ZnO crystallizes in a wurtzite structure. The lattice constants of Ni-doped ZnO nanoparticles decrease slightly when Ni is doped into ZnO. HRTEM analysis indicates that the average diameter of the nanoparticles is about 10–13 nm and no secondary phase was observed with the sensitivity of XRD measurement. Furthermore, two additional Raman peaks were observed, which may be considered to have an origin related to the incorporation of Ni ions into the Zn site of the ZnO lattice. Magnetization measurements under field-cooled and zero-field-cooled conditions reveal that Ni-doped ZnO nanoparticles show ferromagnetic behaviors in room temperature.