A simple chemical route for the synthesis of γ-Fe2O3 nano-particles dispersed in organic solvents via an iron–hydroxy oleate precursor (original) (raw)
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Three-stepped synthesis and characterization of magnetite and maghemite nanoparticles
On the basis of previous findings, here a novel, three-stepped approach is presented aimed at the synthesis of monodispersed superparamagnetic Fe 3 O 4 /γ-Fe 2 O 3 nanoparticles. In the first step of the approach, ferric nitrate nonahydrate, Fe(NO 3) 3 9H 2 O, was sterically hindered in the interstices and cavities of β-Cyclodextrin (β-CD) molecules, followed by a second step of polyol process. The resulting complex was then dispersed in polyethylene glycol (PEG) and the solution was thermally treated, finally yielding a combination of ferric nitrate and PEG in the form Fe(NO 3) 3 9H 2 O-PEG. In the last step, the ferric nitrate/PEG precursor was refluxed in a strong reductive environment, yielding the final superparamagnetic nanoparticles via a thermal decomposition process. The obtained particles were characterized by X-ray diffraction (XRD) and were confirmed to be a mixture of Fe 3 O 4 and/or γ-Fe 2 O 3. Fourier-transformed Infrared (FTIR) spectroscopy confirmed the presence of polyethylene glycol layer on the nanoparticle surface, along with Oleic Acid (OA) and oleylamine (OAm). High-resolution Transmission Electron Microscopy (HRTEM) confirmed satisfactory particle monodispersity, within a size range of 10-12 nm.
A Simple and Effective Method of the Synthesis of Nanosized Fe 2 O 3 particles
Nanosized Iron oxide is prepared by using precipitation method from iron nitrate and liquid ammonia. Thermal analysis shows that synthesized iron oxide shows some weight loss and oxide undergoing decomposition, dehydration or any physical change from TGA curve we observe that Iron oxide shows stable weight loss above 400 0 C. In DTA curve also, there is exothermic and endothermic peak. Which shows phase transition, solid state reaction or any chemical reaction occurred during heating treatment. Morphology is observed by scanning electron microscopy (SEM) shows particles are nanosized. Further morphology observation by Transmission Electron Microscopy (TEM) revels that Iron Oxide has the corundum (Al 2 O 3 ) structure. Magnetic measurements shows that iron oxide has five unpaired electron and strongly paramagnetic character.
Nanosized iron oxide particles were synthesised without the addition of water by autoclaving iron(III) acetate/alcohol and iron(III) acetate/acetic acid/alcohol solutions at 180°C for different time periods. Magnetite was formed in iron(III) acetate/ethanol, whereas hematite was formed in the iron(III) acetate/acetic acid/ethanol system. The average crystallite sizes of 11.1 and 22.6 nm and the stoichiometry of Fe 2.89 O 4 were found for the nanosized magnetite particles. The primary magnetite particles aggregated into regular spheres 5 to 10 μm in size, which can be explained by the specific character of the small, reactive and polar molecules of ethanol. In the iron(III) acetate/octanol system, a mixture of magnetite and hematite was obtained. The average crystallite size of magnetite was up to 22 nm and that of hematite was up to 46.7 nm. In the iron(III) acetate/acetic acid/ethanol system, Eur. J. Inorg.
A novel approach for producing α- and γ-Fe 2O 3 nanoparticles in various media
International Journal of Nanoparticles, 2012
Iron (III) chloride hexahydrate (FeCl 3 .6H 2 O), glycerine, three surfactants and sodium hydroxide (NaOH) are used as the precursors for the preparation of α and γ iron oxide nanoparticles. XRD and TEM are employed to characterise the particles. Novel pathways are identified that may be used to produce either α or γ phases without changing the temperature and through changing the preparation sequence. If the as-prepared particles from the solution produced in the presence of a surfactant, are first washed and then calcinated, the α phase is obtained, whereas if the particles are first calcinated and then washed, the γ phase is produced.
Journal of Asian Ceramic Societies, 2020
The recovery and repurposing of valuable substances from iron-bearing wastes is challenging and vital from economic and environmental perspectives. Herein, maghemite (γ-Fe 2 O 3) particles were synthesized from different iron-containing waste materials by simple chemical precipitation method using HCl, NaOH, and Na 2 CO 3 , followed by calcination. Subsequently, the optimum pH value for the precipitation of iron from solution, and calcination temperature for getting γ-Fe 2 O 3 were found at 12 and 350°C, respectively. The final products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), particle size analysis (PSA), thermogravimetry/differential thermal analysis (TG/DTA), and vibrating sample magnetometry (VSM). The formation of γ-Fe 2 O 3 was anticipated from XRD and FT-IR studies, while TG/DTA data supported their excellent thermal permanence. SEM studies showed that the γ-Fe 2 O 3 particles were relatively irregular, mostly spherical structured with a particle size ranged around 0.2-0.35 μm. PSA confirmed the high specific surface area of γ-Fe 2 O 3 particles, and the largest one was found from the iron dust. VSM measurement assured the existence of ferromagnetic properties in γ-Fe 2 O 3 particles at room temperature. The findings reveal that this procedure is a viable way to prepare γ-Fe 2 O 3 particles from iron-containing waste materials.
Journal of Physical Science
Maghemite (γ-Fe2O3) nanoparticles were synthesised using the coprecipitation method, with different concentrations (5 M, 10 M, 11 M, 12 M and 13.4 M) of sodium hydroxide (NaOH) as the precipitation agent. The resulting powder was characterised using x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscope (TEM). All characterisations were performed at room temperature. The XRD results showed that the γ-Fe2O3 powder was in a single phase for samples synthesised using 11 M, 12 M and 13.4 M NaOH and the crystallite size ranged between 5.74 nm–6.42 nm. TEM observations and analysis showed that the particles were in a cubo-spheroidal shape and the mean physical size of the nanoparticles was between 8.52 nm and 8.59 nm. Hysteresis loop indicated that γ-Fe2O3 nanoparticles have superparamagnetic properties with an acceptable range of saturation magnetisation of 31.08 emu/g–48.88 emu/g and negligible coercivity value. MTT assay demonstrated that the...
Synthesis of γ-Fe2O3 Nanoparticles Capped with Oleic Acid and their Magnetic Characterization
Iranian Journal of Science and Technology Transaction A-science, 2017
In recent years, superparamagnetic iron oxide nanoparticles have attracted a great attention due to their various biomedical applications, such as magnetic resonance imaging, targeted drug delivery, and hyperthermia. In this article, c-Fe 2 O 3 magnetic nanoparticles (Maghemite) were prepared in oleic acid media by co-precipitation method. The oleic acid, a monounsaturated fatty acid was used as the capping and stabilizing agent during the synthesis of the magnetic nanoparticles. Characterization of obtained nanoparticles were performed using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectra (FTIR), and vibrating sample magnetometer (VSM). The crystallite size of c-Fe 2 O 3 nanoparticles was achieved in the range between 16.2 and 26.8 nm. The FESEM demonstrated the regular spheres of c-Fe 2 O 3 nanoparticles. The obtained nanoparticles were coated with oleic acid indicating by FTIR analysis. The resulted oleic acid-coated nanoparticles were shown superparamagnetic properties (*52 emu/g). This suggested method is simple and rapid to fabricate superparamagnetic nanoparticles which make them appropriate candidates for theranostic application in future studies.
One-step solid state synthesis of capped γ - Fe 2 O 3 nanocrystallites
Nanotechnology, 2008
The thermally induced solid state synthesis of soluble organophilic maghemite (γ-Fe 2 O 3) nanocrystallites is described. The solvent-free one-step synthesis involves the reaction in the melt state of Fe(NO) 3 •9H 2 O and RCOOH (R = C 11 H 23 , C 15 H 31) at 240 • C. The method yields well-crystallized nanoparticles of γ-Fe 2 O 3 functionalized with the corresponding aliphatic acid. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) observations reveal composite particles with faceted magnetic cores and average size of 20 nm, which are well capped with the surrounding organic sheath. The Fourier transform infrared (FT-IR) spectra and thermal analysis suggest a bimodal configuration of the organic shell including chemically coordinated and physisorbed molecules of aliphatic acid. The chemical bonding of the carboxylate groups to the surface iron atoms is also indicated by a paramagnetic doublet with unchanged area in the variable temperature Mössbauer spectra. The spinel γ-Fe 2 O 3 particles exhibit perfect structural and magnetic ordering, including the almost ideal ratio of octahedral to tetrahedral positions (5/3) and very low degree of spin canting, as confirmed by in-field Mössbauer spectroscopy. Magnetic measurements demonstrate the suitable properties required in various (bio)magnetic applications like superparamagnetic behavior at room temperature, high saturation magnetization achievable at low applied fields and suppressed magnetic interactions.