A simple chemical route for the synthesis of [gamma]-Fe2O3 nano-particles dispersed in organic solvents via an iron-hydroxy oleate precursor (original) (raw)
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Journal of Industrial and Engineering Chemistry, 2008
A simple chemical route is developed to generate maghemite (g-Fe 2 O 3) nano-particles, dispersed in organic solvents via a thermal decomposition of an iron-hydroxy oleate precursor. An iron-hydroxy oleate precursor was generated by chemical reaction of mixed iron nitrate and oleic acid in ethanol with 30% NH 3 solution with continuous stirring at room temperature. The precursor thus obtained was suspended in hexadecane and then mixed with necessary quantity of oleic acid at room temperature with constant stirring and is further heated to 220 8C/2 h to convert it in to g-Fe 2 O 3 nano-particles. The mixture is allowed to cool slowly to room temperature. The g-Fe 2 O 3 nano-particles remained in dispersed state in hexadecane. The iron-hydroxy oleate molecular precursor and g-Fe 2 O 3 nano-particles are characterized using various physicochemical characterization techniques like DTA/TGA, IR, XRD, vibrating sample magnetometer (VSM), TEM, and EDAX. The characterization results indicated that g-Fe 2 O 3 nano-particles (size 6-15 nm) are obtained by a thermal decomposition of an iron-hydroxy oleate precursor and possess spherical shape. These particles remained dispersed state in organic solvent due to capping action of oleate molecules. The results are quite reproducible and g-Fe 2 O 3 nano-particles can also be dispersed in another organic solvents like kerosene, 2-methyl naphthalene etc.
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.
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.
Low-temperature Synthesis of Maghemite Nanoparticles
Recently, the preparation of magnetic iron oxide nanoparticles has been thoroughly studied due to their unique electric and magnetic properties. Magnetic nanoparticles find uses in a wide range of applications, from data storage and sensors to medical imaging and cancer treatment. Herein, we report a fast and economic chemical procedure for the growth of monodispersed maghemite nanoparticles (NPs) from iron pentacarbonyl Fe(CO) 5. The reaction takes place in a closed vessel where the oxidation strength of dimethylsulfoxide (DMSO) is limited by the reductive strength of liberated carbon monoxide from the initial complex. DMSO "strips" metallic Fe from the intermediate organometallic precursors (e.g. Fe 2 (CO) 9 , Fe 3 (CO) 12), which form at temperatures above 100 0 C, while at the same time oxidizes it in a controlled manner to the desired magnetic phase at temperatures as low as 130 O C, without the need for the classical refluxing step. Oleic acid is also used as a surfactant, thus maintaining a narrow size distribution of NPs. Another advantage of the synthetic route is the short reaction time (30 min).
Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method
Nanomaterials
This paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectr...
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.
Characterization of Nanocrystalline γ–Fe2O3 Prepared by Wet Chemical Method
Journal of Materials Research, 1999
Homogeneous maghemite (g -Fe 2 O 3 ) nanoparticles with an average crystal size around 5 nm were synthesized by successive hydrolysis, oxidation, and dehydration of tetrapyridino-ferrous chloride. Morphological, thermal, and structural properties were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) techniques. Rietveld refinement indicated a cubic cell. The superstructure reflections, related to the ordering of cation lattice vacancies, were not detected in the diffraction pattern. Kinetics of the solid-state phase transition of nanocrystalline maghemite to hematite (a -Fe 2 O 3 ), investigated by energy dispersive x-ray diffraction (EDXRD), indicates that direct transformation from nanocrystalline maghemite to microcrystalline hematite takes place during isothermal treatment at 385 ± C. This temperature is lower than that observed both for microcrystalline maghemite and for nanocrystalline maghemite supported on silica.
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.
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.