A study on the role of moderate optical band gap energy in dielectric properties of NiFe ₂ O ₄ nanoparticles by Ce ion doping for electronic device applications: the effect of doping concentration

This research work employs a sol-gel process to prepare Ni_1-<i>x</i>Ce_<i>x</i>Fe₂O₄ (<i>x</i> = 0.00, 0.05, and 0.10) samples. Ce ion doping was performed to modify the optical band gap for tuning the dielectric properties of NiFe₂O₄ for use in electronic device applications. XRD and Raman spectra confirm the formation and phase purity of synthesized samples. Increasing the concentration of Ce ion content increases the crystallite size in sintered ceramics, and then the crystallite size decreases with <i>x</i> = 0.10 doping concentration of Ce ions. The optical band gap energy decreased with the upsurge in the substitution of Ce ions in NiFe₂O₄ nanoparticles. The insertion of Ce ions in NiFe₂O₄ leads to the development of inter-granular boundaries, causing a decrease in resistivity and a drop in dielectric losses. The obtained spectra showed that the doping concentrations influenced the structural, optical, and dielectric characteristics of NiFe₂O₄ nanoparticles. The dielectric investigation demonstrated frequency-dependent behavior with a consistent decrease in dielectric constant, permittivity, capacitance, resistivity, and impedance with increasing frequency. Tunable dielectric behavior with low dielectric loss in high-frequency and moderate band gap due to desired Ce ion concentration (<i>x</i> = 0.05) regimes makes them potential materials for applications in high-frequency devices, energy storage, and nanoelectronic devices.