Optimizing Cobalt Ferrite Nanocrystal Synthesis Using a Magneto-optical Probe

Tirosh, Einat; Shemer, Gabriel; Markovich, Gil

doi:10.1021/cm052401p

Cited by 87 publications

(58 citation statements)

References 36 publications

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“…The degree of inversion X for ZnFe 2 O 4 nanoparticles prepared by coprecipitation was determined to increase with decreasing particle size (Kamiyama et al 1992). Besides on the size, the degree of inversion also depends on the synthesis method (Ammar et al 2004;Tirosh et al 2006).…”

Section: Introductionmentioning

confidence: 99%

“…In the case of nanoparticles, the structure can substantially deviate from the bulk. The flexibility of the crystal structure is particularly pronounced in the spinel ferrite nanoparticles (Sato et al 1990;Kamiyama et al 1992;Jeyadevan et al 1994;Hamdeh et al 1997;Ammar et al 2004;Makovec and Drofenik 2008;Carpenter et al 1999;Calvin et al 2002;Makovec et al 2009;Morrison et al 2004;Li et al 2000;Sivakumar et al 2007;Tirosh et al 2006). For example, ZnFe 2 O 4 shows paramagnetic behavior as bulk material due to its normal spinel structure, with Zn ions incorporated almost exclusively at tetrahedral sites.…”

Section: Introductionmentioning

confidence: 99%

“…ions adopts tetrahedral sites in 8 nm-sized CoFe 2 O 4 nanoparticles prepared using aqueous coprecipitation. Tirosh et al (2006) compared properties of Co-ferrite nanoparticles with comparable sizes around 10 nm prepared using different methods. Magneto-optical spectroscopy suggested substantial differences in the incorporation of Co 2?…”

Section: Introductionmentioning

confidence: 99%

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Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

et al. 2009

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The Co-ferrite nanoparticles having a relatively uniform size distribution around 8 nm were synthesized by three different methods. A simple coprecipitation from aqueous solutions and a coprecipitation in an environment of microemulsions are low temperature methods (50°C), whereas a thermal decomposition of organo-metallic complexes was performed at elevated temperature of 290°C. The X-ray diffractometry (XRD) showed spinel structure, and the high-resolution transmission electron microscopy (HRTEM) a good crystallinity of all the nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) showed the composition close to stoichiometric (*CoFe 2 O 4 ) for both co-precipitated nanoparticles, whereas the nanoparticles prepared by the thermal decomposition were Co-deficient (*Co 0.6 Fe 2.4 O 4 ). The X-ray absorption near-edge structure (XANES) analysis showed Co valence of 2? in all the samples, Fe valence 3? in both coprecipitated samples, but average Fe valence of 2.7? in the sample synthesized by thermal decomposition. The variations in cation distribution within the spinel lattice were observed by structural refinement of Xray absorption fine structure (EXAFS). Like the bulk CoFe 2 O 4 , the nanoparticles synthesized at elevated temperature using thermal decomposition displayed inverse spinel structure with the Co ions occupying predominantly octahedral lattice sites, whereas coprecipitated samples showed considerable proportion of cobalt ions occupying tetrahedral sites (nearly 1/3 for the nanoparticles synthesized by co-precipitation from aqueous solutions and almost 1/4 for the nanoparticles synthesized in microemulsions). Magnetic measurements performed at room temperature and at 10 K were in good agreement with the nanoparticles' composition and the cation distribution in their structure. The presented study clearly shows that the distribution of the cations within the spinel lattice of the ferrite nanoparticles, and consequently their magnetic properties are strongly affected by the synthesis method used.Electronic supplementary material The online version of this article

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

et al. 2009

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“…This is due to their potential applications in ferrofluids [1], magnetoptics [2], spintronics [3], biomedical applications [4,5], and anodes for batteries [6]. Various fabrication methods have been reported for preparing spinel ferrite nanocrystals for these purposes, e.g., sol-gel methods [7], the ball-milling technique [8], co-precipitation [9], the aerogel process [10], the hydrothermal method [11], the reverse micelles process [12], and the micro-emulsion method [13].…”

Section: Introductionmentioning

confidence: 99%

A Novel Research on Behavior of Zinc Ferrite Nanoparticles in Different Concentration of Poly(vinyl pyrrolidone) (PVP)

Kamari

Naseri

Saion

2014

Metals

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Zinc ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various of concentrations of poly(vinyl pyrrolidone) (PVP), i.e., 0, 15, 40, and 55 g/L, as a capping agent. To stabilize the particles, they were thermally treated at 873 K, as an optimum calcination temperature. The behaviors of the polymeric precursor were analyzed by use of simultaneous thermo-gravimetry (TG) and derivative thermo-gravimetry analyses (DTG). The presence of the crystalline phase in each sample was confirmed by X-ray diffraction (XRD) analysis. The average particle size and the morphology of the nanoparticles were determined by transmission electron microscopy (TEM), and these parameters were found to differ at various concentrations of PVP. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands for all the PVP concentrations and confirmed the absence of organic bands for PVP concentrations less than 55 g/L. Measurements of the magnetization value of the zinc ferrite nanoparticles were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that, in the absence of PVP, the sample exhibited a paramagnetic behavior while, in the presence of PVP, samples have a super-paramagnetic behavior.

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“…Thermal decomposition of metal organic precursors is one of the best ways to prepare the high-quality monodisperse nanoparticles in high-boiling point solvent [35][36][37][38][39][40], such as, metal acetylacetonates [35,36], metal carbonyls, etc. The monodisperse Fe 3 O 4 nanoparticles with good crystallinity and uniform size is obtained by thermal decomposition of the iron acetylacetonates dissolved in 1-octadecene at 300 • C using oleic acid and oleyl amine as surfactants under argon atmosphere.…”

Section: Resultsmentioning

confidence: 99%

Recyclable Fe3O4 Nanoparticles Catalysts for Aza-Michael Addition of Acryl Amides by Magnetic Field

Liu

Luo

et al. 2017

Catalysts

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Abstract:A nanostructure-based catalytic system has the advantages of both homogeneous and heterogeneous catalysis. It is of great significance to develop the sustainable and green process of homogeneous catalytic reaction. We report a novel, efficient and recyclable magnetic Fe 3 O 4 nanoparticles-catalyzed aza-Michael addition reaction of acryl amides, and the magnetic nanoparticles catalysts can be recovered by external magnetic field. Both primary amine and secondary amine can react with various acryl amides providing a good output to target products successfully at room temperature. Further experiments reveal that the magnetic Fe 3 O 4 nanoparticles-based catalyst shows excellent yields, which can be recycled 10 times, and, at the same time, it maintains a high catalytically activity. In this catalytic system, the tedious separation procedures are replaced by external magnetic field, which gives us a different direction for choosing a catalyst in a nanostructure-based catalytic system.

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Optimizing Cobalt Ferrite Nanocrystal Synthesis Using a Magneto-optical Probe

Cited by 87 publications

References 36 publications

Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

A Novel Research on Behavior of Zinc Ferrite Nanoparticles in Different Concentration of Poly(vinyl pyrrolidone) (PVP)

Recyclable Fe3O4 Nanoparticles Catalysts for Aza-Michael Addition of Acryl Amides by Magnetic Field

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