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CoFe2O4 and ZnFe2O4 nanoparticles were synthesized by modified and cost effective sol-gel autocombustion method. X-ray diffraction study confirms the spinel phase formation of face centered cubic lattice with space group Fd3m and without any impurity. Magnetic measurements demonstrate that the CoFe2O4 shows saturation magnetization of 2.73 µB/f.u. where as ZnFe2O4 shows paramagnetic behavior. Magnetic behavior of CoFe2O4 and ZnFe2O4 is confirmed from Mössbauer studies. Effect of sintering on structural, magnetic and cation occupancy of substituted cobalt ferrite is discussed in this paper. [ABSTRACT FROM AUTHOR]

Nanoparticles of Mg0.5Zn0.5Fe2O4 ferrite have been synthesized by co-precipitation method. XRD and Mössbauer spectroscopic results of Mg0.5Zn0.5Fe2O4 annealed at 200 °C, 500 °C and 800 °C are reported. It was observed that the crystallite size increases and the lattice parameter decreases with increase in annealing temperature. The observed decrease in lattice strain supports the increase in crystallite size. The Mössbauer spectra of the samples annealed at 200 °C and 500 °C exhibits superparamagnetic doublets whereas the Mössbauer spectrum of the sample annealed at 800 °C exhibits paramagnetic doublet along with weak sextet of hyperfine interaction. The values of isomer shift resemble the presence of high spin iron ions. The studied ferrite nanoparticles are suitable for biomedical applications. The results are incorporated employing core-shell model and cation redistribution. [ABSTRACT FROM AUTHOR]

Monodisperse nickel nanoparticles (Ni-NPs) were synthesized via a thermal decomposition process. The NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). They were spherical with mean diameter of 4 nm. Zero field cooled (ZFC) and field cooled (FC) magnetization versus temperature data displayed interesting magnetic interactions. ZFC showed a peak at 4.49 K, indicating the super paramagnetic behavior. Magnetic anisotropic constant was estimated to be 4.62x105 erg/cm³ and coercive field was 168 Oe at 3 K. [ABSTRACT FROM AUTHOR]

The nanosized Ni0.3Zn0.7Fe2O4 (~ 15 nm) has been synthesized by high energy ball milling of the bulk powder sample. The sample has been characterized by powder x-ray diffraction, field emission and transmission electron microscopic and dc magnetic measurement techniques. The dc magnetic measurement on the sample indicates that the sample exhibit enhancement of magnetization compared to its counterparts synthesized by chemical methods. Moreover, the system stores the memory of either decrease or increase of magnetic field enabling a magnetic coding of "0" and "1" which can be profitably used in magnetic storage and sensing devices. [ABSTRACT FROM AUTHOR]

In the present manuscript, MnxCo1-xFe2O4 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) nanoparticles have been synthesized with co-precipitation method by annealing at 900 °C and studied the structural and magnetic properties. X ray diffraction pattern reveals the formation of single phase cubic spinel structure with the space group Fd-3m. An impurity peak of a-Fe2O3 has been observed in the XRD patterns of samples with Mn composition, x ≥ 0.4. However, this impurity phase of a-Fe2O3 is not observed in the MnFe2O4 sample synthesized by annealing at 500 oC. FESEM results indicate the formation of nano-sized particles. Magnetic measurements show ferrimagnetic interaction in MnxCo1-xFe2O4 (x≥0) nanoparticles at room temperature. However, MnFe2O4 sample synthesized by annealing at 500 °C shows superparamagnetic behavior. We have fitted the M-H curve of MnFe2O4 synthesized by annealing at 500 °C with modified Langvenin function to confirm superparamagnetism .The correlation between the structural and observed magnetic properties of as synthesized samples nanoparticles will be described and discussed in this paper. [ABSTRACT FROM AUTHOR]

Ni/NiO core-shell nanoparticles have been synthesized by a new simple chemical method. XRD patterns show that the volume fraction of core-shell particles can be controlled by the heat treatment process. The blocking temperature was found to increase with the increase of the volume fraction of Ni/NiO particles, indicating an enhancement in the blocking process. This enhancement can be attributed to the interparticle interaction and exchange bias. [ABSTRACT FROM AUTHOR]

NiFe2O4-SiO2 nanocomposites were prepared by sol–gel method. X-ray diffraction (XRD) method and transmission electron microscope (TEM) were used to identify the phase and sizes (3.5–19 nm) of the sample. AC and DC magnetic measurements showed bellow ∼7 nm the particles are superparamagnet at room temperature. Tln(t/τ0) scaling approach was considered to generate master curves in order to analyze the thermally activated dynamic relaxation phenomena in the nonometric ferrite samples. [ABSTRACT FROM AUTHOR]

We report structural, morphological (particle size, shape) and magnetic properties of nanosized Ni0.5Zn0.5Fe2O4 prepared by high-energy ball milling. We have employed XRD, HRTEM and Mössbauer spectroscopic techniques to achieve the goal. Sample exhibits superparamagnetic behaviour at room temperature. At 21 K the ferrimagnetic ordering and collective excitation along with a strong super-paramagnetic contribution give rise to a mixed magnetic phase. [ABSTRACT FROM AUTHOR]