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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]

Abstract: An ever first attempt to synthesize nanocomposites of SnO2 coated CuFe2O4 has been made using urea–nitrate combustion method. Effect of various concentrations of SnO2 (1, 5, 10 and 20wt.%) at three different sintering temperatures viz., 800, 1000 and 1100°C for optimizing the compound formation has been studied individually. The synthesized materials were characterized by XRD, TEM, HRTEM, SAED, SEM, FT-IR, UV–vis, electrical conductivity and impedance spectra measurements. The XRD spectra reveal that 1100°C-sintered sample is of ultra pure and well-defined crystalline nature irrespective of the concentration of SnO2. The grain size of the materials has been found to get increased as a function of sintering temperature and the extent of SnO2 substitution. The TEM and HRTEM figures evidence the nanocrystalline nature of the product. SAED pattern confirms the presence of single phase and polycrystalline of the final product. The band gap values were calculated from UV–vis spectra, which confirm the lowest band gap value for the 5wt.% SnO2 added sample. The solid-state impedance and the electrical properties of the materials are in favour of the grain and grain boundary effect and the normal behavior of spinel compounds, respectively. [Copyright &y& Elsevier]

Abstract: The La3+ substituted nanocrystalline strontium ferrite has been prepared by citrate combustion method using metal nitrate salts as cation precursors and citric acid as a fuel. The structural characteristics of the compounds have been evaluated using XRD and FTIR. The existence of the single-phase perovskite structure with nanocrystalline size has been confirmed from the X-ray powder diffraction patterns. The stretching and bending vibrations of the metal cations are confirmed from the FTIR spectra. The electrical conductivity of the materials is found to increase with increasing temperature measured by using a modified four-probe technique. The electrochemical behavior has been studied by using potentiostatic polarization method in KOH solutions at two different concentrations of 1 and 2M. From the polarization studies it has been found that the material La0.4Sr0.6FeO3 gives the lowest corrosion rate of 0.001mmpy in 1M KOH solution. [Copyright &y& Elsevier]