Mechanosynthesis of nanostructured magnetic Ni–Zn ferrite

Abstract

Nanocrystalline Ni–Zn ferrite (NiZnFe 2O 4) was directly produced by high energy ball milling of stoichiometric mixture of ZnO, NiO, Fe 2O 3 powders. X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), simultaneous thermal analysing (STA), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) were carried out to characterize the structural, chemical and magnetic aspects of NiZnFe 2O 4 compound. The formation of NiZnFe 2O 4 phase appeared to involve two stages; development of Zn ferrite by diffusion of ZnO in Fe 2O 3 followed by diffusion of NiO in Zn ferrite to form Ni–Zn ferrite. The crystallite size of final product after 60 h of ball milling time was estimated to be 18 nm which increased to 45 nm after annealing at 800 °C for 4 h. After annealing of ball milled powders, the saturation magnetization was increased and coercivity was decreased as lattice defects and internal strain reduced.