Effect of fuel-to-oxidant ratio on phase constituents, microstructure and magnetic properties of NiFe2O4-based composite nanopowder synthesized by sol–gel auto-combustion method

Abstract

In this research, NiFe2O4-based composite nanopowder with 0.8, 1, 1.35, 1.7 fuel-to-oxidant (F/O) ratios was synthesized by sol–gel auto-combustion method. Changes in phase constituents, microstructure and magnetic properties due to changes in F/O ratios were evaluated by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM) techniques. XRD and Raman spectroscopy results show the presence of NiFe2O4, FeNi3, α-Fe2O3 and NiO phases. The amount of nickel ferrite was increased, while the amount of FeNi3 was decreased with increasing F/O ratio from 0.8 to 1.35. Mean crystallite sizes of the samples are in the range of 40–46 nm. FESEM studies depicted the formation of NiFe2O4 particles coexisting with FeNi3 phase. Changes in F/O ratios alter the saturation magnetization values from 37 to 60 emu/g as a result of changes in FeNi3 and NiFe2O4 amounts. Coercivity values are in the range of 135–177Oe. In this research nano-sized NiFe2O4 powders with 0.8, 1, 1.35, 1.7 Fuel to Oxidant (F/O) ratios were synthesized by sol–gel auto-combustion method. FESEM studies depicted the formation of NiFe2O4 particles coexisting with FeNi3 phase. Changes in F/O ratios alter the saturation magnetization values from 37 to 60emu/g as a result of changes in FeNi3 and NiFe2O4 amounts. Coercivity values are in the range of 135 to 177Oe.