Magnetic properties of nanosize NiFe2O4 particles synthesized by sol–gel auto combustion method

A nitrate–citrate gel was prepared from metal nitrates and citric acid by sol–gel auto combustion process, in order to synthesize NiFe2O4 ferrite. X-ray diffraction showed the formation of NiFe2O4 and the inclusion of α-Fe2O3. However, with increasing the calcination temperature, this inclusion phase (α-Fe2O3) decreased. TEM was also used to characterize the microstructure of the nanosize NiFe2O4. Magnetization hysteresis of the nickel ferrite powders was performed at room temperature. It is shown that this powder which is composed of crystalline NiFe2O4 monophase, exhibited Ms = 54 (emu/g) at magnetic field of 2 (kOe).