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Gota, S.; Guiot, Eric; Henriot, M.; Gautier-Soyer, M.

doi:10.1103/physrevb.60.14387

Cited by 167 publications

(80 citation statements)

References 40 publications

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“…Comparative OPA-MBE studies on alumina and neutral magnesia surfaces have found that α-Fe 2 O 3 (0001) grows on α-Al 2 O 3 (0001) [45], but cubic γ-Fe 2 O 3 (001) forms on MgO(001) [23,45]. In-situ structural studies have uncovered transient γ-Fe 2 O 3 [39] or 2ML of FeO phase [46] in the initial stages of OPA-or atomic oxygen assisted (OA)-MBE hematite growth on alumina. By switching from the neutral (001) to the polar (111) magnesia surface, the present work demonstrates that α- Referring back to the bulk atomic models in Figure 1, it is not surprising that we can grow a hexagonal corundum structure on a cubic rock-salt structure, considering the nearly 11/21/2011 prefect match between their oxygen sub-lattices, and the hexagonal in-plane symmetry of the close-packed Mg and O (111) planes that is maintained in the MgO(111)-(1×1)-OH termination.…”

Section: Interface Composition Structure and Morphologymentioning

confidence: 99%

Effects of unreconstructed and reconstructed polar surface terminations on growth, structure, and magnetic properties of hematite films

et al. 2012

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The effects of polar surface stabilization mechanisms on the film growth, phase composition, surface and interface structure, and magnetic properties are explored for polar (1×1) surfaces under equivalent conditions. This study suggests that in addition to the customary strain, spin, and band-gap engineering, control of surface polarity stabilization could also be important for electronic and magnetic device engineering.Cheung et al.2

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Section: Interface Composition Structure and Morphologymentioning

confidence: 99%

Effects of unreconstructed and reconstructed polar surface terminations on growth, structure, and magnetic properties of hematite films

et al. 2012

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“…Consequently, the shape and characteristic features of the Fe2p spectra for specimens CN denote for Fe 3 O 4 , present in the surface layer. 73,85 Considering the features of the O1s spectrum for specimen CN ͑Fig. 11b͒, as an evidence for the presence of Fe 3 O 4 in specimen CN, the following is relevant: the 529.4 eV peak ͑characteristic energy for Fe 3 O 4 ͒, is 2.4% from the total oxygen on the surface and the significantly lower amount of adsorbed water ͑less OH, evidenced by the 2.4% for the 533.2 eV peak from the total O1s͒.…”

Section: Xps Potassium (K In C1smentioning

confidence: 99%

Corrosion Performance of Carbon Steel in Simulated Pore Solution in the Presence of Micelles

Koleva

Wit

et al. 2011

J. Electrochem. Soc.

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This study presents the results on the investigation of the corrosion behavior of carbon steel in model alkaline medium in the presence of very low concentration of polymeric nanoaggregates ͓0.0024 wt % polyethylene oxide ͑PEO͒ 113 -b-PS 70 micelles͔. The steel electrodes were investigated in chloride-free and chloride-containing cement extracts. The electrochemical measurements ͑electrochemical impedance spectroscopy and potentiodynamic polarization͒ indicate that the presence of micelles alters the composition of the surface layers ͑i.e., micelles were indeed absorbed to the steel surface͒ and influences the electrochemical behavior of the steel, i.e., the micelles lead to an initially increased corrosion resistance of the steel whereas no significant improvement was observed within longer immersion periods. Surface analysis, performed by environmental scanning electronic microscopy, energy-dispersive x-ray analysis, and x-ray photoelectron spectroscopy, supports and elucidates the corrosion performance. The product layers in the micelles-containing specimens are more homogenous and compact, presenting protective ␣-Fe 2 O 3 and/or Fe 3 O 4 , whereas the product layers in the micelles-free specimens exhibit mainly FeOOH, FeO, and FeCO 3 , which are prone to chloride attack. Therefore, the increased "barrier effects" along with the layers composition and altered surface morphology denote for the initially increased corrosion resistance of the steel in chloride-containing alkaline medium in the presence of micelles. A well-known fact is that corrosion of steel reinforcement can cause reinforced concrete deterioration and thus affect civil structures durability.1,2 Logically, corrosion-related issues result in a significant economic loss. For example, in the United States, the annual direct cost of bridge infrastructure corrosion was estimated to be $8.3 billion, and the indirect cost was reported to be many times higher. 3In normal conditions, the reinforcing steel embedded in cementbased materials ͑i.e., cement paste, mortar, and concrete͒ is in a passive state because of the high alkalinity ͑pH = 12.6-13.5͒ of the pore solution and the cement paste, respectively. 4,5 However, corrosion can be initiated due to carbonation or chloride contamination. 6 Carbonation can result in a pH drop ͑to about 8-9͒ 7,8 in the pore solution of the bulk cementitious matrix, leading to a general corrosion of the reinforcing steel. In the event of chloride penetration and chloride arrival at the steel/cement paste interface, localized corrosion is initiated; the local pH can drop to even below 6, resulting in fast corrosion propagation. This will cause accelerated damage of the reinforcing steel and possible rapid failure of reinforced concrete. 9To minimize the corrosion processes, various methods and techniques are used. Among them, the polymer-based organic corrosion inhibitors are widely applied because they can provide an easy handling, cost-effective corrosion prevention, delaying corrosion initiation.10-14 The organic inh...

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“…In the case of the Fe 2p spectrum of MnFe 2 O 4 , the presence of Fe 3+ cations yields a well-defined structure 8 eV after the Fe 2p 3/2 peak (711 eV), whereas in Fe 3 O 4 this peak is smeared out due to the presence of both Fe 2+ and Fe 3+ in almost equal proportion. 21 The shape of the Mn 2p also signals the presence of Mn 2+ rather than another oxidation state. Figure 2 shows the Mn 2p electron binding-energy spectrum which consists of spin-orbit-split 2p 3/2 and 2p 1/2 peaks.…”

Section: A Structural and Chemical Characterizationsmentioning

confidence: 99%

Epitaxial growth and ferrimagnetic behavior of MnFe2O4(111) ultrathin layers for room-temperature spin filtering

et al. 2011

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We report on the epitaxial growth and physical properties of spinel MnFe 2 O 4 (111) thin films with thicknesses down to 2 nm. The thin films, grown on α-Al 2 O 3 (0001) single crystals or Pt(111) buffer layers by oxygen-assisted molecular beam epitaxy, exhibit high structural order with sharp interfaces and low roughness. The electrical and magnetic properties are carefully investigated and it is shown that MnFe 2 O 4 (111) ultrathin films keep an insulating and ferrimagnetic behavior at room temperature. Special attention is given to the iron/manganese valence state and the cationic ordering. X-ray absorption spectroscopy and magnetic circular dichroism measurements reveal that thin films contain mainly Fe 3+ and Mn 2+ cations, distributed predominantly in a normal spinel structure. This study proves the high potential of MnFe 2 O 4 to be used as a magnetic tunnel barrier for spin filtering applications at room temperature.

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Atomic-oxygen-assisted MBE growth of α−Fe2O3

Cited by 167 publications

References 40 publications

Effects of unreconstructed and reconstructed polar surface terminations on growth, structure, and magnetic properties of hematite films

Effects of unreconstructed and reconstructed polar surface terminations on growth, structure, and magnetic properties of hematite films

Corrosion Performance of Carbon Steel in Simulated Pore Solution in the Presence of Micelles

Epitaxial growth and ferrimagnetic behavior of MnFe2O4(111) ultrathin layers for room-temperature spin filtering

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