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Copper doped nickel ferrites Ni (1− x ) Cu x Fe 2 O 4 (where x =0.2, 0.4, 0.6) nanoparticles are prepared by co-precipitation method and sintered at 600 °C. The XRD study confirms the formation of single-phase cubic spinel Ni–Cu ferrites. The particle size increases with Cu substitution. FT-IR spectra confirm the absorption bands around 554–547 cm −1 for the tetrahedral sites and around 448–450 cm −1 for the octahedral sites. The inclusion of copper shifts the tetrahedral band to lower values. The saturation magnetization ( M s ) and remanent magnetization ( M r ) decrease with increase in copper concentration and the coercivity ( H c ) is found to increase for all the compositions sintered at 600 °C. The dielectric constant decreases drastically for all the compositions and reaches a constant value. These nanoparticles can be tested for humidity sensing applications. [ABSTRACT FROM AUTHOR]

Manganese ferrite (MnFe 2 O 4 ) and cobalt doped manganese ferrite (Mn 1− x Co x Fe 2 O 4 ) with x =0, 0.2, 0.4, 0.6, and 0.8 are synthesized at pH 11 and an annealing temperature of 900 °C, through co-precipitation technique. The particle sizes are found to be in the range of 30–35 nm. The varying dopant concentrations influence the crystalline edges, surface morphology and magnetic properties of the samples. Particle size initially increases for the incorporation of cobalt up to x =0.6 and then decreases. As cobalt concentration increases, the saturation magnetization increases up to x =0.6 and then decreases. Stretching and bending of bonds at tetrahedral and octahedral sites respectively are noticed and they shift towards the longer wavelengths. The samples are tested for their application as adsorbents of toxic heavy metal Cr(VI). The adsorption efficiency variations with dopant concentrations of samples, quantity of adsorbent and concentrations of chromium are studied. [ABSTRACT FROM AUTHOR]

Manganese ferrite (MnFe 2 O 4 ) samples of good homogeneity were synthesized at pH 8 and pH 11 for different annealing temperatures through wet chemical synthesis by a co-precipitation method. Particle size increases and crystalline nature improved with increase in annealing temperatures as indicated in XRD peaks. EDS study confirmed the purity of the prepared samples. The cubic spinel structure and bond stretching of samples were analyzed through FTIR. The surface studies were carried out using SEM micrographs. The SAED patterns predicted crystalline nature and the particle size was found to be 20–40 nm as confirmed through TEM analysis. The magnetic hysteresis curves were analyzed using VSM and super paramagnetic nature of soft magnetic material was reported for samples prepared at pH 8. The dielectric and conductivity studies confirm that the material can be used in high frequency applications. The application of the synthesized ferrite as adsorbent of toxic heavy metal Cr(VI) has been successfully tested. The adsorption and removal depend on quantity of adsorbent, annealing temperatures of sample, pH of sample and initial concentration of Cr(VI). [ABSTRACT FROM AUTHOR]

Copper substituted cobalt–nickel mixed ferrite nano particles are synthesized by co-precipitation method and the samples are sintered at 130°C, 600°C and 900°C. The effects of sintering on structural and magnetic properties are studied using XRD analysis and VSM studies. The particle sizes are found to be 12nm and 32nm for the samples sintered at 600° and 900°C respectively and the degree of crystallinity of the sample increases with increasing sintering temperature. The absorption bands shift to lower values on sintering the samples. The saturation magnetization (M s ), remanent magnetization (M r ) and coercivity (H c ) increase on sintering the samples at 600°C and 900°C. EDX results confirm the presence of Co, Ni, Cu, Fe and O without any impurities. [ABSTRACT FROM AUTHOR]

Nanocrystalline zinc (Zn)-substituted cobalt ferric oxide (CoFe2O4) was prepared through chemical co-precipitation; the prepared samples were annealed at 600°C, 750°C and 900°C. The crystallite size, microstructure and magnetic properties of the prepared and annealed samples were studied by using X-ray powder diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDS) and Vibrating Sample Magnetometry. The structural investigations carried out by XRD reveal that the particle size and lattice constant of single phase spinal structured Zn substituted CoFe2O4 increase with the increase of annealing temperature. The FTIR spectra for the samples measured in the range of 4000–400cm−1 exhibit symmetric stretching mode of vibration of tetrahedral and octahedral sites. Furthermore, Zn substituted CoFe2O4 nanoparticles have the crystallite size in the range ~13–65nm, as confirmed by TEM. The elemental analysis was obtained from EDS. Finally, increased annealing temperature resulting in increased particle size and the impact on magnetic properties of CoFe2O4 nanoparticles is a significant finding of this study. [ABSTRACT FROM AUTHOR]

Nanopowders of CoFe2O4 are synthesized via wet chemical co-precipitation processing at pH 8. The synthesized nanoferrite powders are annealed at various temperatures (350°C, 700°C and 1050°C) and are characterized. X-ray diffraction (XRD) patterns indicate the crystalline nature of CoFe2O4 nanopowders. Transmission electron microscope (TEM) investigations show, anisotropic shapes like cubic, hexagonal and spherical morphology of nanoparticles with average particle size 38–85nm. Dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests the material is suitable for high frequency applications. AC conductivity increases with frequency. The saturation magnetization (M s), remanant magnetism (M R) and coercivity (H C) increases with applied field. [ABSTRACT FROM AUTHOR]