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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]

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]

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]