Chemical control on the size and properties of nano NiFe2O4 synthesized by sol–gel autocombustion method

Nickel ferrite nanoparticles have been synthesized by sol–gel auto combustion route. The significant role played by nitric acid added to the precursor solution in controlling the reaction rate phase purity, crystallinity, crystallite size, thermal and magnetic properties of nanoparticles was explored and reported. Also, the influence of annealing on the properties were studied. Samples of average crystallite size ranging from 10 nm to 40 nm have been obtained by controlling the HNO3 concentration and by increasing the annealing temperature. The size-dependent structural, thermal and magnetic properties were investigated and reported. The Hopkinson peak was observed for all the crystalline samples near the Curie temperature. The highest value 47.3 emu/g of saturation magnetization was obtained for the sample prepared with higher concentration (6 mol/L) of HNO3.