Investigation on size dependent structural and magnetic behavior of nickel ferrite nanoparticles prepared by sol–gel and hydrothermal methods

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In the present article, we report the synthesis of Nickel ferrite (NiFe 2O 4) nanoparticles using sol–gel and hydrothermal methods. In the sol–gel synthesis process we used glycolic acid as a chelating agent for the preparation of NiFe 2O 4 nanoparticles. In this process, glycolic acid acts as a fuel which decomposes the metal complexes at low temperature and yields impurity free NiFe 2O 4 nanocrystalline structures. In the hydrothermal process the NiFe 2O 4 nanoparticles were synthesized at low temperature (∼160 °C). The size of NiFe 2O 4 nanoparticles obtained through hydrothermal process was smaller (∼9 nm) than that of sol–gel process (∼27 nm). The synthesized nanoparticles were characterized by thermogravemetric analysis (TGA)/differential scanning calorimetery (DSC), Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy and vibrating sample magnetometer (VSM). The magnetic measurements of nanoparticles were done at room temperature and found that NiFe 2O 4 nanoparticles synthesized by sol–gel method exhibit a ferromagnetic behavior with a saturation magnetization 31 emu g −1 while the NiFe 2O 4 nanoparticles synthesized by hydrothermal process exhibit a superparamagnetic behavior with a saturation magnetization of 46 emu g −1.