Ordered Array of Single Adatoms with Remarkable Thermal Stability:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Au</mml:mi><mml:mo>/</mml:mo><mml:msub><mml:mi>Fe</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="bold">O</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>001</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math>

Novotný, Zbyněk; Argentero, Giacomo; Wang, Zhiming; Schmid, Michael; Diebold, Ulrike; Parkinson, Gareth S.

doi:10.1103/physrevlett.108.216103

Cited by 115 publications

(90 citation statements)

References 40 publications

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“…27 Foreign metal atoms deposited onto this surface adsorb in an oxygen-bridging site in one specific location of the unit cell. 39,[41][42][43] The force-relaxed structure of a Co adatom (Co 2+ ) in such site is shown in Figure 6(a).…”

Section: B Dft Resultsmentioning

confidence: 99%

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Co on Fe3O4(001): Towards precise control of surface properties

Gargallo-Caballero

Martín-García

Quesada

et al. 2016

The Journal of Chemical Physics

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A novel approach to incorporate cobalt atoms into a magnetite single crystal is demonstrated by a combination of x-ray spectro-microscopy, low-energy electron diffraction, and density-functional theory calculations. Co is deposited at room temperature on the reconstructed magnetite (001) surface filling first the subsurface octahedral vacancies and then occupying adatom sites on the surface. Progressive annealing treatments at temperatures up to 733 K diffuse the Co atoms into deeper crystal positions, mainly into octahedral ones with a marked inversion level. The oxidation state, coordination, and magnetic moments of the cobalt atoms are followed from their adsorption to their final incorporation into the bulk, mostly as octahedral Co2+. This precise control of the near-surface Co atoms location opens up the way to accurately tune the surface physical and magnetic properties of mixed spinel oxides.

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Section: B Dft Resultsmentioning

confidence: 99%

“…Among them, based on reported work 39,[41][42][43] and our DFT calculations, we have considered the adatom site on top of two surface oxygen cations in a bridge configuration, the surface octahedral positions, and the subsurface octahedral positions. The latter, as described in the Sec.…”

Section: Discussionmentioning

confidence: 99%

Co on Fe3O4(001): Towards precise control of surface properties

Gargallo-Caballero

Martín-García

Quesada

et al. 2016

The Journal of Chemical Physics

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“…53 We recall that the Fe(001)-p(1 × 1)O substrate does not posses any preferential site for the atom stabilization (exploited, for example, in Ref. 54). We should mention that the oxygen adlayer could hinder the Cr atoms mobility; however, our previous measurements 47 demonstrate that the oxygen does not affect the Cr intralayer mass transport.…”

Section: Resultsmentioning

confidence: 99%

Self-organized chromium oxide monolayers on Fe(001)

et al. 2013

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The oxygen-saturated Fe(001)-p(1 × 1)O surface has been used as a template to stabilize two-dimensional Cr oxides on Fe(001). Cr deposition at 400 • C leads to two different well-ordered phases, depending on the amount of Cr deposited. In the submonolayer regime a novel c(4 × 2) overlayer self-assembles on the Fe(001)-p(1 × 1)O surface, saturating for a coverage of about 0.75 monolayers. This phase becomes unstable for higher coverages, when a ( √ 5 × √ 5)R27 • superstructure emerges. The structural and electronic details of the two one-layer-thick oxides are studied by combining high-resolution scanning tunneling microscopy, low-energy electron diffraction, Auger electron spectroscopy, and density functional theory.

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“…The initial incorporation occurred already at room temperature due to the presence of the cation vacancies in the SCV reconstruction, and bulk diffusion into the bulk coincided with the onset of bulk diffusion at around 550 K. Atomistic simulations [493] When Au is evaporated onto the freshly prepared Fe 3 O 4 (100)-(√2×√2)R45° surface at room temperature it adsorbs exclusively as Au 1 adatoms up to a coverage of 0.13 ML (here, ML is defined as 1 atom (√2×√2)R45° unit cell, see Figure 80). The adatoms appear between the Fe oct rows in STM images and are immobile at room temperature [259]. DFT+U calculations suggest the Au is twofold coordinated to the surface oxygen atoms that do not have a subsurface Fe tet neighbour within the SCV reconstruction (referred to here as the "not-blocked" site, but termed the "narrow site" in ref.…”

Section: Metalsmentioning

confidence: 99%

“…As such the Au/Fe 3 O 4 (100) is a promising model system to study the fundamentals of single-atom catalysis. For coverages above 0.13 ML Au, clusters nucleate and coexist with adatoms [259]. Simple Monte Carlo simulations based on a hit-and-stick model suggest that a significant number of Au atoms impinging on the surface begin to land in a unit cell already occupied by a Au atom at a coverage of ≈0.13 ML [502], which likely results in Au dimer formation.…”

Section: Metalsmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

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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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Ordered Array of Single Adatoms with Remarkable Thermal Stability:Au/Fe3O4(001)

Cited by 115 publications

References 40 publications

Co on Fe3O4(001): Towards precise control of surface properties

Co on Fe3O4(001): Towards precise control of surface properties

Self-organized chromium oxide monolayers on Fe(001)

Iron oxide surfaces

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