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Abstract: CuFe2O4/xCeO2 (x =0, 1, 5, 10 and 20wt%) nanocomposites have been prepared by urea–nitrate combustion method. The particle size of the as-prepared CuFe2O4/5wt% CeO2 nanocomposite is 5–10nm which has been revealed from TEM and HRTEM images. The as-synthesized materials have been sintered at four different temperatures (600, 800, 1000 and 1100°C) for 5h. The XRD analysis of the samples reveals that the prepared materials possess tetragonal structure and have the composite behaviour. The 1100°C sintered samples have further been characterized by FT-IR, UV–vis, SEM, ac electrical conductivity, dielectric constant, loss tangent, and Mössbauer spectra. The SEM images clearly show that CeO2 grows on the surface of the CuFe2O4. The electrical properties enumerate the ferrimagnetic behaviour of the synthesized materials. The Mössbauer spectra confirm both the inverse spinel structure of the prepared materials and the Fe3+ state of iron ions. [Copyright &y& Elsevier]

Metallic ferrites are investigated as prospective materials for different applications especially as anodes in extractive metallurgy. CuFe2O4, one of the important ferrites, is envisaged for substituting the carbon anode in Hall–Heroult cells. A single step combustion process has been used for the synthesis of CuFe2O4 powder from cupric nitrate, ferric nitrate and urea. The experimental conditions for maximum conversion efficiency of the precursor powders have been optimized. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) have confirmed the formation, structure and homogeneity of the as-prepared powders. The detailed physical, electrical and structural characterization of the materials have been carried out for the specimens obtained on sintering at different temperatures up to 1000 °C. [Copyright &y& Elsevier]

The structural and electrical properties of magnesium-substituted nickel ferrite having the general formula of Ni1-xMgxFe2O4 (x=0, 0.3, 0.6, 0.9) has been studied as a function of magnesium ion concentration. The materials have been prepared by citrate gel process using metal nitrate salts as a cation precursors and citric acid as gelating agent. The powder X-ray diffraction pattern confirms fcc structure for the synthesized compound. The variation of lattice parameter and the tetrahedral radius increases with increase in Mg2+ ion concentration. The AC electrical parameters such as dielectric constant (#x03B5;′) and loss tangent (tan δ) for all the systems have been studied as a function of frequency in the range 50 Hz to 10 kHz at room temperature. A maximum DC electrical conductivity of 3.3 S cm-1 was obtained at a temperature of 1000°C and a AC electrical conductivity of 10.94×10-6at 10 kHz was observed in the composition x=0.6 i.e. for Ni0.4Mg0.6Fe2O4 compound which may be due to the maximum Fe2+ concentration in the octahedral sites. The dielectric constant follows the Maxwell''s–Wagner interfacial polarization and the relaxation peaks were observed in the dielectric loss properties. The FTIR spectra show the characteristic peaks of ferrite sample. The morphological features were studied using scanning electron microscope. [Copyright &y& Elsevier]