Synthesis of NiFe₂O₄ nanoparticles by organic surfactants-assisted sol-gel auto-combustion method, characterization and determination of band gap

Recently, nickel ferrite has attracted attention due to its multiple applications in storage devices, microwave devices, gas sensors, ferrofluids and catalysts. Nickel ferrites have excellent optical properties owing to their small band gap, which makes them suitable as a photocatalyst.

Among methods to synthesize nanocrystalline NiFe₂O₄, combustion method seems to be one of the facile and one step methods, since it allows the preparation of nanocrystalline NiFe₂O₄ with an equiaxial shape and narrow size distribution. Applying surfactants, which are composed from molecules along with sol–gel method can improve the properties of the synthesized powders.

In this present study, the sol–gel auto-combustion method is applied for synthesizing the NiFe₂O₄/CTAB and NiFe₂O₄/SDS nanocomposite, using nickel nitrate, iron nitrate, ammonia, citric acid and CTAB and SDS as surfactant. The nanoparticles were characterized by XRD, SEM, FT-IR and DRS. Powder XRD analysis and FT-IR spectroscopy confirmed formation of NiFe₂O₄ spinel phase. The particles size was estimated from SEM data. The energy band gaps were calculated by Kubelk-Munk model from UV–Vis absorption.