Investigation of the effective parameters on the synthesis of Ni-ferrite nanocrystalline powders by coprecipitation method

In this work, synthesis of nanostructured NiFe₂O₄ powders by coprecipitation method using novel precursors, followed by calcination was investigated for the first time. The synthesis was started by dissolving Fe and Ni chlorides and ammonium ferrous sulfate in deionized water. After stirring, the precipitating agent of NaOH was added to the solution and after 1 h aging, the resultant precipitates were washed with deionized water and acetone. Then the powder was characterized and the effects of different parameters such as molarity of precipitant, calcination temperature and the molar ratio of Ni²⁺ ion to the total iron ions were studied. It is concluded that an increase in molarity of precipitant can decrease the calcination temperature. The best conditions giving a single phase Ni-ferrite were using of 2.2 molar NaOH, calcination temperature of 900 °C and the molar ratio of nickel to iron as 0.5. The crystallite size of resulting ferrites was below 50 nm.