Colloidal Synthesis and Characterization of Tetrapod-Shaped Magnetic Nanocrystals

Cozzoli, P. Davide; Snoeck, E.; García, M. A.; Giannini, Cinzia; Guagliardi, Antonietta; Cervellino, Antonio; Gozzo, F.; Hernando, A.; Achterhold, Klaus; Ciobanu, Nelica; Parak, Fritz Guenter; Cingolani, R.; Manna, Liberato

doi:10.1021/nl061112c

Cited by 140 publications

(139 citation statements)

References 51 publications

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“…Developments with aberration-corrected TEM have revolutionized our ability to characterize such species, and over recent years an astounding level of control has been developed in the synthesis of nanomaterials. Iron and iron oxide nanoparticles of all kinds of different shapes and sizes including nanorods [609], nanocubes [610][611][612], and tetrapods [613] can be created by decomposing precursors such as iron pentacarbonyl in a ternary surfactant mixture under mild thermal conditions. In Figure 101, for example, the addition of oleic acid, sodium oleate, and tetraoctylammonium bromide modified the growth rate of different facets such that cubes and octaherda were produced.…”

Section: Realistic Materialsmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

488

463

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The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe 3 O 4 ), maghemite (γ-Fe 2 O 3 ), hematite (α-Fe 2 O 3 ), and wüstite (Fe 1-x O) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe 3 O 4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment, and because it is an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.The best understood iron oxide surface at present is probably Fe 3 O 4 (100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Fe oct -O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10 Such straightforward preparation of a monophase termination is generally not the case for other iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe (0001) is the most studied hematite surface, but 2 difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe 3 O 4 (111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe 1-x O and α-Fe 2 O 3 (0001) islands was recently challenged and a new structure based on a thin film of Fe 3 O 4 (111) on α-Fe 2 O 3 (0001) was proposed. The merits of the compet...

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Section: Realistic Materialsmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

488

463

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“…Among the chemical routes used so far to synthesize iron oxide based nanomaterials, it is worth to mention hydrothermal synthesis [15,16], coprecipitation [17], solgel method [18], and colloidal chemistry method [19]. These methods usually involve synthesizing an iron-based precursor gel, followed by decomposing the gel or precursor into the designed crystalline iron oxide phase at an elevated temperature.…”

Section: Introductionmentioning

confidence: 99%

Ultrafine Magnetite Nanopowder: Synthesis, Characterization, and Preliminary Use as Filler of Polymethylmethacrylate Nanocomposites

Russo

Acierno

Palomba

et al. 2012

Journal of Nanotechnology

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Magnetite (Fe 3 O 4 ) nanoparticles prepared by microwave-assisted hydrothermal synthesis have been characterized in terms of morphological and structural features. Electron micrographs collected in both scanning (SEM) and transmission (TEM) modes and evaluations of X-ray powder diffraction (XRD) patterns have indicated the achievement of a monodispersed crystallite structure with particles having an average size around 15-20 nm. Structural investigations by Micro-Raman spectroscopy highlighted the obtainment of magnetite nanocrystals with a partial surface oxidation to maghemite (γ-Fe 3 O 4 ). Preliminary attention has been also paid to the use of these magnetite nanoparticles as filler for a commercial polymethylmethacrylate resin. Hybrid formulations containing up to 3 wt% of nanoparticles were prepared by melt blending and characterized by calorimetric and thermogravimetric tests. For sake of comparison, same formulations containing commercial Fe 3 O 4 nanoparticles are also reported. Calorimetric characterization indicates an increase of both glass transition temperature and thermal stability of the nanocomposite systems when loaded with the synthesized magnetite nanoparticles rather then loaded with the same amount of commercial Fe 3 O 4 . This first observation represents just one aspect of the promising potentiality offered by the novel magnetic nanoparticles when mixed with PMMA.

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“…[5,10,[27][28][29][30][31][32][33][34][35][36][37][38] This method allows the synthesis of maghemite particles with different shapes, for example, spheres, [10,29,[36][37][38] hollow spheres, [34] diamonds, [39] or tetrapods. [33] In our group, we are interested in organometallic synthesis based on the hydrolysis of the [ZnA C H T U N G T R E N N U N G (c-C 6 H 11 ) 2 ] complex for the preparation of ZnO NPs of controlled size and shape. [40,41] The kinetics of the reaction, and therefore the size and shape of these particles, are well controlled by the organic ligands introduced in the reaction medium.…”

Section: Introductionmentioning

confidence: 99%

An Organometallic Approach for Very Small Maghemite Nanoparticles: Synthesis, Characterization, and Magnetic Properties

et al. 2008

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Maghemite (gamma-Fe(2)O(3)) nanoparticles stabilized by long-alkyl-chain amines are synthesized by using an organometallic approach. This method consists of the hydrolysis and oxidation of an organometallic precursor, Fe[N(SiMe(3))(2)](2), in the presence of amine ligands as stabilizing agent in an organic solvent, namely tetrahydrofuran or toluene. Whatever the experimental conditions, particles with a diameter of 2.8 nm are obtained. The use of high-resolution transmission electron microscopy and wide-angle X-ray scattering, together with Mössbauer spectroscopy and SQuId magnetometry, allows a complete characterization of these particles. Herein, we show that their structure is composed of a well-ordered core surrounded by a more disordered shell. The size of the latter varies from 0.65 to 0.50 nm depending on the experimental conditions and is of prime importance for the understanding of the magnetic properties. We demonstrate that the shorter the alkyl chain length of the amine 1) the better the crystallinity of the particle's core and 2) the stronger the interparticle interactions.

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Colloidal Synthesis and Characterization of Tetrapod-Shaped Magnetic Nanocrystals

Cited by 140 publications

References 51 publications

Iron oxide surfaces

Iron oxide surfaces

Ultrafine Magnetite Nanopowder: Synthesis, Characterization, and Preliminary Use as Filler of Polymethylmethacrylate Nanocomposites

An Organometallic Approach for Very Small Maghemite Nanoparticles: Synthesis, Characterization, and Magnetic Properties

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