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, NiFe 2 O 4 -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 NiFe 2 O 4 , FeNi 3 , a-Fe 2 O 3 and NiO phases. The amount of nickel ferrite was increased, while the amount of FeNi 3 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 NiFe 2 O 4 particles coexisting with FeNi 3 phase. Changes in F/O ratios alter the saturation magnetization values from 37 to 60 emu/g as a result of changes in FeNi 3 and NiFe 2 O 4 amounts. Coercivity values are in the range of 135-177Oe. Graphical Abstract In this research nano-sized NiFe 2 O 4 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 NiFe 2 O 4 particles coexisting with FeNi 3 phase. Changes in F/O ratios alter the saturation magnetization values from 37 to 60emu/g as a result of changes in FeNi 3 and NiFe 2 O 4 amounts. Coercivity values are in the range of 135 to 177Oe.

Dielectric and Magnetic Study of NiCuZn Spinel Ferrites

“…As a result magnetic moment of NiFe 2 O 4 is the magnetic moment of Ni 2+ ions. 6 The substitution of Zn 2+ (nonmagnetic ion) for Ni 2+ in ferrite lattice leads to increase in saturation magnetization. It is well known that Zn 2+ have a strong preference for occupation of tetrahedral site, Ni 2+ and Cu 2+ prefer to occupy octahedral sites whereas Fe 3+ ions partially occupy tetrahedral and octahedral sites.…”

“…Thus a fraction of Fe 3+ at tetrahedral sites are forced to move to octahedral sublattice, as a result magnetic moment of tetrahedral sublattice decreases as Fe 3+ have larger magnetic moment than Cu 2+ which they replace. 6 The squareness factor (M r /M s ) plays a key role in determining the magnetic hardness of a material. The value of squareness factor between 0.05 and 0.5 specifies the magneto-static couplings via single domain, 27 {Formatting Citation}.…”

“…Addition of copper modifies magnetic and electrical properties. 6 Zinc doped ferrites are commercially useful for high frequency applications like radio frequency coils, antennas & read & write magnetic cores. Tagba Sasmaz Kuru et al studied doped ZnFe 2 O 4 (Cu 0.5 Zn 0.5 Fe 2 O 4 and Ni 0.5 Zn 0.5 Fe 2 O 4 ) spinel ferrite and found that at lower frequencies, ac conductivity and dielectric constant of CuZn ferrite is larger than NiZn ferrite.…”

“…15 Furthermore, the amalgamation of zinc can densify the ferrite, enhance electromagnetic properties, reduces magneto-restriction and anisotropy. 6 The diamagnetic ions substitution in controlled way is known for improved magnetic assets of ferrites. 15 Thus by changing Zn content remanent and saturation magnetization, permeability, hysteresis loss, frequency response can be tailored.…”