Influence of Cerium substitution on structural, optical, and electrical transport properties of Ni-Nano ferrites prepared by Citrate gel auto combustion method

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The citrate-gel auto combustion is chosen to the preparation nanocrystalline materials of NiCeXFe2-X O4(X = 0.0 to 0.040 with variation of 0.010). XRD confirmed the crystalline phase of the prepared samples, and by using Debye Scherrer equation the crystalline size was calculated to be 26–14 nm. Lattice parameter variation was observed for the series of samples, which indicates that it obeys Vegard's law. Agglomerated structures and particles observed in the SEM images are in the nanometre region. Two FTIR bands were found in the FTIR spectrum, which attribute the stretching frequencies of tetrahedral (1) and octahedral (υ2) bands, respectively. The Urbach energy of the present Ce doped Ni NFs was found to decrease with increase in the Ce dopant content. It is an indication that enrichment of rare-earth oxide into ferrite base results in more order and decrease of disorderness. Dielectric studies of the samples carried out by LCR meter, analysed results of AC conductivity (σAC), impedance(Z), dielectric constant (ε/), dielectric loss (Tan δ). The σ AC of the samples increased with increasing temperature and dopant concentration. Impedance spectroscopy revealed semi-circular behaviour, and the effect of grain and grain boundaries on electrical conductivity was investigated. The dielectric permittivity and loss decreased as increasing frequency, which phenomena was explained by Koop’s theory of mechanism.