Abstract
TEM image showed a mono-phase cubic agglomerated crystals with size of about 20nm. The agglomeration behavior can be attributed to the magneto-static interaction between particles or experiencing a permanent magnetic moment by nanoparticles proportional to their volume. [Display omitted]
•Cr-substituted Ni–Zn ferrites were synthesized through Egg-white route.•Effect of substitution on structural and electromagnetic properties was studied.•A proposed mechanism for complexation and ferrite formation was suggested.•An appropriate cation distribution was estimated.
Nano-crystalline ferrites with formula Ni0.8Zn0.2CrxFe2−xO4 (x=0.0–1.0) was synthesized using Egg-white auto-combustion method. An appropriate mechanism for complexation and ferrite formation was suggested. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and a.c. electrical conductivity measurements were utilized to study the effect of Cr-substitution and its impact on particle size and electro-magnetic properties of the investigated ferrite. X-ray diffraction revealed single-phase cubic structure. The decrease in lattice parameter with increasing chromium was discussed in the view of ionic radii. TEM exhibited cubic agglomerated crystals with sizes between 10 and 20nm. The decrease in the saturation magnetization and coercivity estimated through VSM measurements with increasing Cr-content indicated the preferential occupation of Cr3+ ions in the octahedral sites. Ac-conductivity measurements revealed semiconducting behavior of the entire investigated samples at high temperature and revealed a magnetic transition from ferromagnetic to paramagnetic for the samples with Cr-content up to 0.2. The conductivity values as well as the conduction activation energies indicated that the Cr3+ ions do not participate in the conduction and thus limit the Fe2+–Fe3+ conduction by blocking up Fe2+–Fe3+ transformation.