Nickel nitrate hexahydrate (Ni (NO3)2·6H2O) solution

In order to prepare 0.2 M solution, 2.909 g of nickel nitrate hexahydrate was dissolved in 50 ml distillated water to make 50 ml of 0.2 M solution and 5.406 g of Ferric chloride salt (FeCl₃) was dissolved in distillated water to make 50 ml of 0.4 M solution of Ferric Chloride (FeCl₃). Both solutions were mixed properly on magnetic stirrer at 200 rpm homogenously at 80 °C for 30 min, then placed outside room temperature. Sodium hydroxide (12 g) was mixed in 100 ml distilled water to make 100 ml of 2.0 M solution of mineralized sodium hydroxide (NaOH), which was then added drop wise using syringe as precipitating agent until the solution gained required pH of 8–9, while constantly stirred at 400 rpm and maintained at a temperature of 70 ± 5 °C for 2 h till brown precipitates were formed. After that, the stirrer was switched off and the magnetic particles settled gradually. The brown precipitate product was cooled at room temperature and the precipitated solution was washed several times with distilled water and neutralized with ethanol (C₂H₅OH) to eliminate unwanted impurities from the sample by centrifugation at 4000 rpm. The obtained substance was placed in an oven at 70 °C for 24 h, and after drying, the dried nano powder was ground and calcined at 350–550 °C for 3 h in a muffle furnace to obtain pure NiFe₂O₄, which was then crushed by pestle to obtain the final product in a fine powder form.