Superlattices of Iron Nanocubes Synthesized from Fe[N(SiMe
 3
 )
 2
 ]
 2

Dumestre, Frédéric; Chaudret, Bruno; Amiens, Catherine; Renaud, Philippe; Fejes, Peter

doi:10.1126/science.1092641

Cited by 526 publications

(257 citation statements)

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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

499

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

499

463

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“…[22][23][24][25] In previous studies, we have evidenced the interest of organometallic complexes for the preparation of metal nanoparticles of controlled size, shape and organization. [26][27][28][29][30][31][32][33] We have shown that this methodology can be extended to the synthesis of nanoparticles of metal oxides with a precise control of morphology. [34][35][36][37] which can be, in a second step, oxidized into well crystallized nanoparticles of the corresponding oxides, without coalescence.…”

Section: Introductionmentioning

confidence: 99%

Organometallic approach for platinum and palladium doping of tin and tin oxide nanoparticles: structural characterisation and gas sensor investigations

et al. 2006

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Platinum and palladium surface doped tin nanoparticles have been obtained by decomposition of [Pt 2 (dba) 3 ] and [Pd(dba) 2 ] organometallic precursors, respectively, in a colloidal suspension of tin/ tin oxide core-shell nanoparticles of uniform size (E13 nm), in anisole under 1 bar of carbon monoxide at room temperature. The particles can be isolated as pure solids and present effective doping ratios [Pt]/[Sn] and [Pd]/[Sn] of 2.5 and 3.1%, respectively. These nanomaterials have been characterized by means of transmission electron and high-resolution transmission electron microscopies (TEM and HRTEM), Energy Dispersive X-ray spectroscopy (EDX), photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (EXAFS and XANES). The TEM micrographs show spherical nanoparticles whose size and size distribution are essentially similar to those of the initial Sn/SnO x material. HRTEM, EDX, XPS and X-ray absorption spectroscopy (XAS) studies at the Pd and/or Sn-K edge show the conservation of the composite nature of the particles that consist of a tin(0) core covered with a layer of tin oxides on which the doping element is deposited under the form of crystalline metallic platelets of size near 2 nm. The thermal oxidation of these Pt-or Pd-doped tin materials yields nanoparticles of crystallized SnO 2 covered with crystallites of Pt or Pd oxides, as demonstrated by XRD, XPS and XAS experiments, without coalescence or size change. In the oxidised Pd-doped material, EXAFS analysis combined with HRTEM, point towards the formation of two main Pd disordered oxide phases: a rather pure oxopalladate Pd 3.5 O 4 -type phase at the surface of the particle and a mixed Pd/Sn phase having a PdO structure-type at the interface Pd oxide/Sn oxide. The thermal oxidation process can be easily achieved onto the silicon platform of a micro-machined device after integration of the Pt-or Pd-doped Sn/SnO x colloidal suspension by drop deposition. The first electrical measurements indicate remarkable behaviours of the as-obtained microsensors when exposed to traces of carbon monoxide. In addition to the expected large increase of sensitivity of the doped relatively to the undoped sensitive layer measured in humid atmosphere, a surprising and unprecedented inversion of sensitivity from undoped to Pt-and Pd-doped sensors has been observed in dry atmosphere.

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“…[3] Uniquely, the Ni(II) amide was reported to be unstable, decomposing to a black solid at room temperature. [2] The Mn, Fe, and Co silylamides are thermally stable and have proven to be valuable synthons in diverse applications, [4][5][6][7][8][9][10][11][12][13] but the unstable nature of Ni{N(SiMe3)2}2 has hindered its further use. Its instability is especially striking because several other stable, homoleptic Ni(II) amides are known.…”

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confidence: 99%

The Instability of Ni{N(SiMe₃)₂}₂: A Fifty Year Old Transition Metal Silylamide Mystery

et al. 2015

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The characterization of the unstable NiII bis(silylamide) Ni{N(SiMe3)2}2 (1), its THF complex Ni{N(SiMe3)2}2(THF) (2), and the stable bis(pyridine) derivative trans‐Ni{N(SiMe3)2}2(py)2 (3), is described. Both 1 and 2 decompose at ca. 25 °C to a tetrameric NiI species, [Ni{N(SiMe3)2}]4 (4), also obtainable from LiN(SiMe3)2 and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of NiII to NiI and the stabilization of 4 through dispersion forces.

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Superlattices of Iron Nanocubes Synthesized from Fe[N(SiMe ₃ ) ₂ ] ₂

Cited by 526 publications

References 20 publications

Iron oxide surfaces

Iron oxide surfaces

Organometallic approach for platinum and palladium doping of tin and tin oxide nanoparticles: structural characterisation and gas sensor investigations

The Instability of Ni{N(SiMe₃)₂}₂: A Fifty Year Old Transition Metal Silylamide Mystery

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Superlattices of Iron Nanocubes Synthesized from Fe[N(SiMe 3 ) 2 ] 2

Cited by 526 publications

References 20 publications

Iron oxide surfaces

Iron oxide surfaces

Organometallic approach for platinum and palladium doping of tin and tin oxide nanoparticles: structural characterisation and gas sensor investigations

The Instability of Ni{N(SiMe3)2}2: A Fifty Year Old Transition Metal Silylamide Mystery

Contact Info

Product

Resources

About

Superlattices of Iron Nanocubes Synthesized from Fe[N(SiMe ₃ ) ₂ ] ₂

The Instability of Ni{N(SiMe₃)₂}₂: A Fifty Year Old Transition Metal Silylamide Mystery