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Abstract: Nanocrystalline CuFe2O4 and CuFe2O4/xSnO2 nanocomposites (x=0, 1, 5wt%) have been successfully synthesized by one-pot reaction of urea–nitrate combustion method. The transmission electron microscope study reveals that the particle size of the as synthesized CuFe2O4 and CuFe2O4/5wt%SnO2 are 10 and 20nm, respectively. The SnO2 coating on the nanocrystalline CuFe2O4 was confirmed from HRTEM studies. The resultant products were sintered at 1100°C and characterized by XRD and SQUID for compound formation and magnetic studies, respectively. The X-ray diffraction pattern shows the well-defined sharp peak that confirms the phase pure compound formation of tetragonal CuFe2O4. The zero field cooled (ZFC) and field cooled (FC) magnetization was performed using SQUID magnetometer from 2 to 350K and the magnetic hysteresis measurement was carried out to study the magnetic properties of nanocomposites. [Copyright &y& Elsevier]

Nanocomposites are a cohesive class of materials, which have many technological applications due to their excellent properties, realizable within the range of 1–100 nm sizes. Ferrite nanocomposites have been used as the potential candidate materials for photocatalytic and electrocatalytic anodes for oxidation of organic compounds like phenol, anodes for lithium batteries, inert anode for aluminium electrolysis, etc. Recently these are envisaged as an eco-friendly substitute for carbonaceous materials in electrochemical applications. In the present study the CuFe 2 O 4 /SnO 2 nanocomposites have been prepared by a novel combustion method. The TEM figure confirms the nanocrystalline nature of the as-synthesized product. XRD spectra show the well-defined crystalline nature and a phase transition of tetragonal to cubic on increased SnO 2 substitution. The band gap values calculated from the UV-Vis spectra are in the vicinity of semiconducting range. The maximum a.c. electrical conductivity of 1.75×10 -3 S · cm -1 was obtained for CuFe 2 O 4 /5% SnO 2 composition. The impedance spectrum also confirms the semiconducting behavior of the materials. [ABSTRACT FROM AUTHOR]

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]

Abstract: Ultrafine powders of nanocrystalline CuFe2O4 and CuFe2O4/10wt.% SnO2 nanocomposites are prepared by a urea–nitrate combustion method. Phase pure and highly crystalline CuFe2O4 (tetragonal structure) and CuFe2O4/SnO2 (cubic structure) are obtained after sintering at 1100°C. The average particle size is 10–20 and 20–30nm, respectively. Both the nanoferrite anodes have an excellent specific capacity of greater than 800mAhg−1 versus Li metal. It is concluded that SnO2 doping improves the coulombic efficiency of copper ferrite anodes from 65 to 99.5% via an enhanced structural stability. [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]