Formation of γ-Fe2O3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction study

Jørgensen, Jens-Erik; Mosegaard, Lene; Thomsen, Line Elnif; Jensen, Torben R.; Hanson, Jonathan C.

doi:10.1016/j.jssc.2006.09.033

Cited by 162 publications

(143 citation statements)

References 20 publications

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“…The lattice parameter calculated in the present study was equal to 8.349 Å. Furthermore, if we compare value obtained for the lattice parameter calculated in the present study with those found in literature it can be seen a good agreement [30][31][32]. In good agreement with previous studies [33], the slight broadening of the diffraction lines can be interpreted in terms of small sized crystallites.…”

Section: Discussionsupporting

confidence: 90%

Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Balaș

Ciobanu

Burtéa

et al. 2017

Metals

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Abstract:We report the synthesis of dextran-coated iron oxide magnetic nanoparticles (DIO-NPs) with spherical shape and uniform size distribution as well as their accumulation and toxic effects on Jurkat cells up to 72 h. The characterization of dextran-coated maghemite nanoparticles was done by X-ray diffraction and dynamic light scattering analyses, transmission electron microscopy imaging, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, magnetic hysteresis, and relaxometry measurements. The quantification of DIO-NPs intracellular uptake showed a progressive accumulation of iron as a function of time and dose accompanied by additional lysosome formation and an increasing darkening exhibited by a magnetic resonance imaging (MRI) scanner. The cytotoxicity assays revealed a decrease of cell viability and a loss of membrane integrity in a time-and dose-dependent manner. Exposure to DIO-NPs determined an increase in reactive oxygen species level up to 72 h. In the first two days of exposure, the level of reduced glutathione decreased and the amount of malondyaldehyde increased, but at the end of the experiment, their concentrations returned to control values. These nanoparticles could be used as contrast agents for MRI but several parameters concerning their interaction with the cells should be taken into consideration for a safe utilization.

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Section: Discussionsupporting

confidence: 90%

Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Balaș

Ciobanu

Burtéa

et al. 2017

Metals

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“…(1) cubic structure with random distribution of the vacancies (space group Fd3m); (2) vacancies distributed as the Li cations in LiFe 5 O 8 (space group P4 3 32) [140] (3) an ordered distribution of the vacancies with tetragonal symmetry and a three-fold doubling along the c-axis (space group P4 1 2 1 2) [145].…”

Section: Bulk Defects 29mentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

487

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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“…It is noteworthy that these surfaces are terminated simultaneously by Fe 3+ and O 2À sites. [19][20][21] There are equal numbers of octahedral and tetrahedral Fe 3+ ions on the {110} plane (4.05 atoms per nm 2 ), but only octahedral Fe Figure S3). Consequently, the surface of the g-Fe 2 O 3 nanorod is relatively rich in octahedral Fe 3+ ions.…”

mentioning

confidence: 99%

“…Consequently, the surface of the g-Fe 2 O 3 nanorod is relatively rich in octahedral Fe 3+ ions. More importantly, the length of the FeÀO bond (0.2091 nm) is greater than that in the tetrahedrally coordinated environment (0.1837 nm), [20] making it more reducible and reactive. achieved at 220 8C.…”

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confidence: 99%

Rod‐Shaped Fe₂O₃ as an Efficient Catalyst for the Selective Reduction of Nitrogen Oxide by Ammonia

et al. 2012

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Nanorust: Fe2O3 nanomaterials with controllable crystal phase and morphology have been successfully fabricated. The γ‐Fe2O3 nanorods that are enclosed by the reactive {110} and {100} facets are highly active and distinctively stable for selective catalytic reduction of NO with NH3. The picture shows the shape and surfaces and the surface atomic configurations of the preferentially exposed {110} and {001} planes.

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Formation of γ-Fe2O3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction study

Cited by 162 publications

References 20 publications

Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Iron oxide surfaces

Rod‐Shaped Fe₂O₃ as an Efficient Catalyst for the Selective Reduction of Nitrogen Oxide by Ammonia

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Formation of γ-Fe2O3 nanoparticles and vacancy ordering: An in situ X-ray powder diffraction study

Cited by 162 publications

References 20 publications

Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Synthesis, Characterization, and Toxicity Evaluation of Dextran-Coated Iron Oxide Nanoparticles

Iron oxide surfaces

Rod‐Shaped Fe2O3 as an Efficient Catalyst for the Selective Reduction of Nitrogen Oxide by Ammonia

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Product

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Rod‐Shaped Fe₂O₃ as an Efficient Catalyst for the Selective Reduction of Nitrogen Oxide by Ammonia