Characterization of the “native” surface thin film on pure polycrystalline iron: A high resolution XPS and TEM study

Bhargava, Gaurang; Gouzman, I.; Chun, C. M.; Ramanarayanan, T. A.; Bernasek, Steven L.

doi:10.1016/j.apsusc.2006.09.047

Cited by 348 publications

(199 citation statements)

References 14 publications

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“…The Fe 2p 3=2 and Fe 2p 1=2 peaks have a binding energy of 706.8 eV and 719.7 eV, respectively, which is consistent with already reported binding energies of metallic iron. 35,36 The XP spectra of all iron oxide films in Fig. 2 show the typical Fe 2p peak shape for stoichiometric magnetite.…”

Section: Resultsmentioning

confidence: 99%

Modifying magnetic properties of ultra-thin magnetite films by growth on Fe pre-covered MgO(001)

Schemme

Krampf

Bertram³

et al. 2015

Journal of Applied Physics

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Iron oxide films were reactively grown on iron buffer films, which were deposited before on MgO(001) substrates to analyze the influence of the initial iron buffer layers on the magnetic properties of the magnetite films. X-ray photoelectron spectroscopy and low energy electron diffraction showed that magnetite films of high crystalline quality in the surface near region were formed by this two-step deposition procedure. The underlying iron film, however, was completely oxidized as proved by x-ray reflectometry and diffraction. The structural bulk quality of the iron oxide film is poor compared to magnetite films directly grown on MgO(001). Although the iron film was completely oxidized, we found drastically modified magnetic properties for these films using the magnetooptic Kerr effect. The magnetite films had strongly increased coercive fields, and their magnetic in-plane anisotropy is in-plane rotated by 458 compared to magnetite films formed directly by one step reactive growth on MgO(001). V C 2015 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 99%

Modifying magnetic properties of ultra-thin magnetite films by growth on Fe pre-covered MgO(001)

Schemme

Krampf

Bertram³

et al. 2015

Journal of Applied Physics

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“…Studies performed on polycrystalline [4] as well as on single crystalline [5] surfaces have shown that the oxidation of iron can be understood in the framework of the coupled current mechanism introduced by Fromhold and Cook more than 50 years ago [6]. While those experiments explain very well the observed growth kinetics, the actual composition of the native oxide is still a matter of debate and is obviously highly dependent on preparation parameters like temperature and surface orientation ( [7][8][9][10][11] and references therein). X-ray absorption spectroscopy at the L edges was recently used to characterize the extent of oxidation or reduction processes arising at the interface between Fe and other transition metal oxides (CoO and NiO) [12].…”

mentioning

confidence: 99%

How Metallic Fe Controls the Composition of its Native Oxide

et al. 2008

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We have studied in situ the oxidation of ultrathin iron layers and monitored the chemical changes induced by subsequent deposition of Fe metal using hard x-ray absorption spectroscopy. The site sensitivity of the technique allows us to quantify the composition of the layer throughout the oxidation or deposition process. It is found that the thin native oxide incorporates a significant fraction of Fe atoms remaining in a metallic configuration even in the saturated state. Subsequent deposition of Fe leads to a complete reduction of the oxide that adopts an FeO-like structure containing Fe 2 sites only. DOI: 10.1103/PhysRevLett.101.056101 PACS numbers: 81.15.ÿz, 61.05.cj, 81.16.Pr In recent years, intensive research has been conducted on transition metal oxide compounds, thin films, and multilayers due to their potential use as building blocks in magnetic structures like spin valves and magnetic tunnel junctions (for a review, see [1] and references therein). Recently, metal -native-oxide multilayers (MNOM, produced by metal deposition and subsequent oxygen exposure) have been proposed as new compounds combining high magnetization and low conductivity [2]. In these systems, the buried oxide possesses magnetic properties that strongly deviate from any bulk iron oxide phase [2,3]. However, the influence of the surrounding metal on the structure of the oxide is not yet identified and prevents clear understanding of the observed magnetic properties of MNOM systems.The oxidation of iron itself has been extensively studied in the past decades. Studies performed on polycrystalline [4] as well as on single crystalline [5] surfaces have shown that the oxidation of iron can be understood in the framework of the coupled current mechanism introduced by Fromhold and Cook more than 50 years ago [6]. While those experiments explain very well the observed growth kinetics, the actual composition of the native oxide is still a matter of debate and is obviously highly dependent on preparation parameters like temperature and surface orientation ([7-11] and references therein). X-ray absorption spectroscopy at the L edges was recently used to characterize the extent of oxidation or reduction processes arising at the interface between Fe and other transition metal oxides (CoO and NiO) [12]. Remarkably, the interaction of Fe with its own oxide phases was never quantitatively studied before.In this Letter, we present a quantitative x-ray absorption spectroscopy (XAS) study of the oxidation of ultrathin iron layers and the changes induced by subsequent coverage with Fe. The sensitivity of the XAS signal to the oxidation state and the local environment of the absorbing atom is used to follow the evolution of the oxide's structure in a quantitative and site specific manner. The use of ultrathin layers (in contrast to other studies which used thick substrates [4,5,[7][8][9]) allows one to directly resolve the intrinsic composition of the growing oxide and disentangle the influence of the substrate.The experiment was performed in situ in...

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“…[14] Similar two-peak structure was observed earlier for the same Pt/Vulcan system with peaks centred at ∼532 and ∼535 eV, which were assigned to C O bond and water. [7] Taking into account that the latter binding energies were not charge referenced and that O 1s binding energy associated with water is close to 533.8 eV, [8] one may find a good correspondence between these data. The low energy component is observed in the O 1s spectra of bimetallic nanocomposite at different U b and can be assigned to Pt-O bond as well.…”

Section: Resultsmentioning

confidence: 87%

XPS/TEM characterisation of PtAu/C cathode electrocatalysts prepared by metal vapour synthesis

Vasil’kov

Naumkin

Volkov

et al. 2010

Surface & Interface Analysis

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Monometallic Pt/C, Au/C and bimetallic Pt-Au/C nanocomposites have been prepared by metal vapour synthesis using Vulcan XC-72R carbon support. X-ray photoelectron spectroscopy and transmission electron microscopy were used to evaluate the structure and properties of the metallic nanoparticles. XPS data show the absence of any significant electron transfer in bimetallic Pt-Au/C system prepared by successive deposition of Au and Pt nanoparticles. The only evidence of Pt-Au interaction is the narrowing Au 4f peaks in Pt-Au/C catalyst in comparison with those of Au/C system.

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Characterization of the “native” surface thin film on pure polycrystalline iron: A high resolution XPS and TEM study

Cited by 348 publications

References 14 publications

Modifying magnetic properties of ultra-thin magnetite films by growth on Fe pre-covered MgO(001)

Modifying magnetic properties of ultra-thin magnetite films by growth on Fe pre-covered MgO(001)

How Metallic Fe Controls the Composition of its Native Oxide

XPS/TEM characterisation of PtAu/C cathode electrocatalysts prepared by metal vapour synthesis

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