The oxidation state of Fe(100) after initial oxidation in O2

Roosendaal, S. J.; Asselen, B. van; Elsenaar, J.W.; Vredenberg, A. M.; Habraken, F.H.P.M.

doi:10.1016/s0039-6028(99)01006-7

Cited by 222 publications

(115 citation statements)

References 24 publications

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“…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 a compact UHV deposition chamber (base pressure 1 10 ÿ9 mbar) mounted on the A1 beam line of the DORIS III storage ring (DESY, Hamburg). The Fe K-edge absorption signal was recorded by measure of the total electron yield and fluorescence yield.…”

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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].…”

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confidence: 99%

“…Several studies on iron oxidation at room temperature (RT) reported the possible presence of metallic Fe in the oxide layer [2,5,9], without being able to disentangle the influence of the thick Fe substrate on the origin of the signal. The use of ultrathin Fe layers allows us to address this question in a more quantitative manner.…”

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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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How Metallic Fe Controls the Composition of its Native Oxide

et al. 2008

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“…The difference in the shape of the spectra was due to the changes in the electronic states and local structure of Fe. 16 The Fe K absorption-edge energy of the reduced thin film was about 1.5 eV lower than that of the SrFeO 2.5 thin film. This chemical shift indicates that the Fe oxidation state in the CaH 2 -treated thin-film sample was reduced to that close to Fe…”

Section: Thin Film Growth and Characterizationmentioning

confidence: 87%

Reduction and Oxidation of Transition-Metal Oxide Thin Films: Solid-State Chemistry with Epitaxially Grown Thin Films

Shimakawa

2013

Bulletin of the Chemical Society of Japan

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Reduction and oxidation of perovskite-structure transition-metal oxide thin films are highlighted. Oxygen ions are released from and incorporated into the perovskite-structure framework during the reduction and oxidation. Lowtemperature topochemical reduction reaction with CaH 2 enables us to prepare infinite-layer structure oxide thin films containing Fe and Ni. With the epitaxially grown thin film samples, anisotropic rearrangement and transfer of oxygen ions in the structures have been revealed. Selective reduction of layers in artificial superlattices was also found, and the observed behavior suggests that the oxygen-ion mobility in the artificial superlattices was confined within the twodimensional brownmillerite layer. Specific structural features play important roles in the oxygen-ion transfer in solids at low temperatures. The obtained results would be a key to develop technologies related to energy and the environment.

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“…It has been shown in previous studies [1,[9][10][11][12][13][14][15] that the peak positions of Fe 2p 1/2 and Fe 2p 3/2 depend on the ionic states of Fe. The positions of the satellite peaks for the Fe 2p 1/2 and Fe 2p 3/2 peaks are also very sensitive to the oxidation states and these peaks have been used for qualitatively determining the ionic states of iron.…”

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confidence: 86%

Natural Oxidation of thin Fe Films on V Buffer Layer

et al. 2017

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We have studied oxidation kinetics of Fe thin film under atmospheric conditions using the fact that metallic iron is a ferromagnet but ultrathin natural iron oxides are approximately nonmagnetic at room temperature. As a consequence, oxidation is associated with a loss in total Fe magnetic moment. Results show that the sample with an initial Fe thickness equal to 10 nm oxidize relatively fast (time constant τ = 0.05 day), whereby a constant amount of 2.5 nm of metal is transformed into oxides. For lower iron initial thickness (di = 4 nm) the time constant for oxidation significantly increases reaching a value of 2 days. Furthermore, X-ray photoelectron spectroscopy studies performed after 144 days of oxidation revealed formation of hematite (α-Fe2O3) thin film on the metallic rest of iron.

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The oxidation state of Fe(100) after initial oxidation in O2

Cited by 222 publications

References 24 publications

How Metallic Fe Controls the Composition of its Native Oxide

How Metallic Fe Controls the Composition of its Native Oxide

Reduction and Oxidation of Transition-Metal Oxide Thin Films: Solid-State Chemistry with Epitaxially Grown Thin Films

Natural Oxidation of thin Fe Films on V Buffer Layer

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