Influence of cerium substitution on structural, magnetic and dielectric properties of nanocrystalline Ni–Zn ferrites synthesized by combustion method

Nickel–Zinc (Ni–Zn) ferrites substituted by cerium (Ce) and having the chemical composition Ni0.5Zn0.5Ce x Fe2−x O4 (x = 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) were synthesized by combustion method using the organic fuel urea as reducing agent. The effects of cerium substitution on the structural, magnetic and dielectric properties of Ni–Zn compounds have been evaluated. X-ray diffraction patterns indicate that the Ni0.5Zn0.5Ce x Fe2−x O4 crystallizes into cubic spinel structure initially and secondary phase emerged along with main spinel phase when the Ce3+ content is increased. The elemental composition analysis confirms the stoichiometric presence of expected elements in the samples. Scanning electron microscope and high-resolution transmission electron microscope images reveal the nature of grain growth and the particle size of the synthesized samples. Fourier transform infrared spectroscopy confirms the formation of spinel phase and predicted the shifting of bands corresponding to Fe–O vibrations towards higher wavenumbers compared to undoped Ni–Zn ferrite. Magnetic characterization studies reveal that the substitution of Ce3+ into the Ni–Zn ferrite leads to a significant change in saturation magnetization and coercivity values. A plot of dielectric constant (ɛ′) versus applied electrical frequency measured at room temperature shows the normal dielectric behavior of the spinel ferrites. The introduction of Ce3+ rare earth ions into Ni–Zn ferrites samples is found to affect the values of both dielectric constant and AC conductivity.