Effects of Ni and Annealing Temperature on Crystal Structure and Magnetic Properties of MnNi-Fe2O4 Nanoparticles

Manganese nickel ferrite (MnNi-Fe<inf>2</inf>O<inf>4</inf>) nanoparticles have been synthesized by co-precipitation method. In this research, the effects of Ni concentration (0.2-0.8M) and annealing temperature (400-1000°C) on the structural and magnetic properties of nanoparticles were studied. Ferrite samples were characterized by X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM) and Fourier Transform Infrared (FTIR) spectroscope. The XRD patterns showed that nanoparticles possess cubic spinel structure that indicated by peaks of (220), (311), (400), (511) and (440). The crystallite size decreased with the increase of Ni concentration (23.5-4.5 nm) and increased with the increase of annealing temperature (14.8-49.3 nm). Stretching vibration on octahedral and tetrahedral of metal-oxygen from FTIR spectra was observed at 354.9-462.9 cm^-1 and 586.3-601.7 cm^-1, respectively. Magnetic properties of ferrite sample were analyzed by Vibrating Sample Magnetometer (VSM). The saturation magnetization (Ms) lay in the range of 11.07-20.7 emu/g and the Coercivity (Hc) decreases with the increase of annealing temperature (217.0-167.0 Oe).