Sol–gel mediated surface modification of nanocrystalline NiFe2O4 spinel powders with amorphous SiO2

Surface modification of nanocrystalline NiFe2O4 spinel particles with amorphous SiO2 by the sol–gel process at 350 °C was demonstrated. Amorphous phase of the SiO2 layer was evaluated by X-ray diffraction technique. Structural coordination of the pristine and SiO2 coated NiFe2O4 particles as investigated by employing FTIR analysis. Thickness of the SiO2 layer was investigated through transmission electron microscopy and it was identified to be ∼10–23 nm over nanocrystalline NiFe2O4 particles. The magnetic behavior of pristine and surface modified NiFe2O4 particles were investigated using vibrating sample magnetometer (VSM). Magnetic studies showed the retention of magnetic property of surface modified NiFe2O4 particles with the reduced saturation magnetization and coercivity compared to the pristine NiFe2O4 particles, which is respectively due to the lower fraction of the magnetic component and the formation of interfacial structure.