Synthesis and magnetic properties of flower-like FeCo particles through a one pot polyol process (original) (raw)
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Structural and magnetic characterization of soft-magnetic FeCo alloy nanoparticles
Journal of Electron Spectroscopy and Related Phenomena, 2006
Soft-magnetic FeCo alloy nanoparticles with diameters less than 100 nm are prepared by ball milling. X-ray photoemission spectroscopy (XPS) and X-ray magnetic circular dichroism (XMCD) are used to characterize these particles. While the XPS spectrum from the as-prepared sample clearly shows Co photoemission peaks, no sign of Fe is observed in the same spectrum. However, Fe photoemission peaks appear after 1 h of Ar ion sputtering. A quantitative analysis of the XPS spectra shows an increase of Fe concentration versus sputtering time until the Fe:Co ratio of the bulk alloy is reached. In addition, the narrow scan Fe and Co 2p XPS spectra show that Co is more oxidized than Fe. All these measurements indicate that the nanoparticles have a Co shell and an Fe-rich core. They further demonstrate the usefulness of XPS combined with depth-profiling via sputtering to obtain element-and chemically-sensitive structural information on nanoparticles. XMCD as an element-specific magnetic analysis tool further reveals that Fe and Co are ferromagnetically coupled in these particles. The information obtained is useful for establishing a structure-property relation for the studied material that is expected to have applications as a soft magnetic material at high temperatures.
Facile Synthesis of Feco Nanoparticles by One-Pot Polyol Process
European Chemical Bulletin, 2019
Ferromagnetic FeCo nanoparticles were prepared by a simple one-pot polyol process and followed by simple annealing treatment. The prepared ferromagnetic FeCo nanoparticles have a spherical shape and the size was controlled by the annealing temperature. Importantly, single FeCo phase was obtained at 400°C and these samples have spherical shape and size about 50 nm. While at a higher temperature (at 600°C) the nanoparticles have very lower aggregation and have higher coercivity. The prepared FeCo nanoparticle at low temperature with excellent magnetic properties is to be considered as a potential candidate for many applications.
Journal of Magnetism and Magnetic Materials, 2010
Properties of FeCo nanocrystalline intermetallic powders prepared by salt-matrix hydrogen reduction of a milled Fe 2O 3-Co 3O 4 mixture were investigated. The product of 72 ks ball-milling at 350 rpm was CoFe 2O 4 nanopowder. Reduction of this powder for 3.6 ks by hydrogen at 750 °C resulted in the formation of Fe 0.67Co 0.33 stoichiometric compound. Scanning electron microscopy, electron dispersive spectrometry, X-ray diffraction and vibrating sample magnetometry were used to characterize the nanopowder. Using a salt-matrix (NaCl as a dispersion medium) resulted in the decrease of the reduction temperature and improvement of the morphology and magnetic properties of the nanopowder. Dispersion of the ball-milled product in Hexan resulted in further improvements of the magnetic properties.
One-pot synthesis of high magnetization air-stable FeCo nanoparticles by modified polyol method
Materials Letters, 2013
High magnetization FeCo nanoparticles with different Fe/Co ratios have been successfully synthesized by surfactant free simple modified polyol method. Polyethylene glycol (PEG) was used as solvent and reducing agent simultaneously in this synthesis process. All the synthesized samples of FeCo nanoparticles were annealed at 600 1C before characterizations. X-ray diffraction (XRD) data on the samples confirm formation of a body-centered-cubic single phase structure in all the compositions. Transmission Electron Microscopy (TEM) data suggest that the annealed FeCo nanoparticles are of 50-90 nm in size. The use of PEG and the annealing procedure employed ensure that the obtained nanoparticles are stable in air. This observation is well supported by both the analysis of Energy Dispersive Spectrometry (EDS) and the images of TEM which establish the formation of a thin passive oxide layer over the FeCo nanoparticles thereby resulting in the stability of the nanoparticles. The physical Property Measurement System (PPMS) reveals that the Fe 60 Co 40 composition among all the samples exhibit highest saturation magnetization of 230.14 emu/g at 5 K.
Preparation of magnetic FeCo nanoparticles by coprecipitation route
Current Applied Physics, 2007
Magnetic FeCo nanoparticles with high saturation magnetization (M s = 148 emu/g) at 15 kOe were prepared by a coprecipitation route. The value of M s for FeCo nanoparticles depends on the ratio of Fe to Co components. The size of the nanoparticles was confirmed by transmission electron microscopy (TEM) images, and morphology of the nanoparticles was obtained by field emission scanning electron microscopy (FE-SEM) images. The crystal structure of the nanoparticles dependent on annealing was characterized by X-ray diffraction data. The magnetic properties were characterized by saturation magnetization from a hysteresis loop by VSM.
Advanced Powder Technology, 2014
Fe 1Àx Co x (x = 0.1, 0.15, 0.2, 0.25, 0.3 and 0.5) powders were prepared by different milling-annealing treatments, and magnetic properties were investigated based on microstructure. Elevated heating times led to an increase in crystallite size, and decrease in lattice parameter. Up to 20 min annealing, series 3 powders showed a decrease in microstrain 2.5 times more than series 2. The coercivity (H C ) of 1-step milled and 60 min annealed Fe 50 Co 50 alloys decreased rigorously from 60 Oe to 19 Oe due to strain relief (from 0.3% to 0.08%) and grain growth (from 30 nm to 40 nm). For series 2 alloys, the H C (up to 60 min heating) increased from 72 Oe to 90 Oe, and decreased (up to 100 min heating) to 70 Oe. Compared to series 1, extra milling treatment of series 2 causes an increase in magnetization saturation (M S ) due to completion of alloying and grain refinement. Also, compared to series 2, extra annealing treatment for series 3 resulted in larger values of M S caused by stain relief.
Structural and magnetic study of the annealing of FeCo nanoparticles
J. Mater. Chem., 2009
Post-synthesis thermal treatments are often used to induce the crystallization of amorphous nanoparticles obtained by wet chemical synthesis in order for them to display the physical properties of the bulk. We have studied the structural and magnetic evolution of FeCo magnetic nanoparticles synthesized via an organometallic route during a soft controlled annealing treatment. Despite very mild conditions, the structural study, carried out using WAXS, EXAFS and M€ ossbauer spectroscopy, evidences the presence of carbon atoms in the as-synthesized structure and their continuous insertion in the structure upon heating, as they form a rather ordered structure including carbides, before being expelled from the particles as the crystallization of the bcc alloyed phase takes place at higher annealing temperatures. The magnetic properties, recorded along the process, accordingly show highly depleted values as the carbon atoms insert in the structure, and reach the Ms bulk value as the bcc phase is restored.
Journal of Physics: …, 2011
Co nanoparticles stabilized by polyvinylpyrrolidone (PVP) have been prepared using modified polyol process. When 5 mmol of PVP was used, aggregated nanoparticles with irregular shapes were resulted; whereas on increasing the PVP concentration to 10 mmol, highly spherical nanoparticles were obtained. In the present work, the influence of non-ionic stabilizer viz. PVP on the synthesis of spherical nanoparticles and their structural, macromagnetic properties have been reported.