Changes induced at Ni/Cr alloy surfaces by annealing and oxygen exposure

Jeng, Shin-Puu; Holloway, Paul H.; Asbury, Douglas A.; Hoflund, Gar B.

doi:10.1016/0039-6028(90)90792-7

Cited by 24 publications

(19 citation statements)

References 27 publications

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“…NiO dominates the surface oxide during the early stages of oxidation, which is in agreement with the literature in the temperature regime of the present study. 6,7,11,52,8,52 The impact of Cr on NiO nucleation, and the wide range of surface features that emerge early in the oxidation process, illustrates the complexity of alloy surface chemistry. Consideration must be given to the preferred nucleation and growth site for each constituent metal in the alloy and their corresponding oxide phase, and the effects of the oxide growth on surrounding phases.…”

Section: ■ Discussionmentioning

confidence: 99%

From Alloy to Oxide: Capturing the Early Stages of Oxidation on Ni–Cr(100) Alloys

Blades

Reinke

2018

ACS Appl. Mater. Interfaces

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The interaction of oxygen with Ni−Cr(100) alloy surfaces is studied using scanning tunneling microscopy (STM) and spectroscopy (STS) to observe the initial steps of oxidation and formation of the alloy−oxide interface. The progression of oxidation was observed for Ni(100) and Ni−Cr(100) thin films including Ni−8 wt % Cr(100) and Ni−12 wt % Cr(100), which were grown on MgO(100) in situ. These surfaces were exposed to between 1 and 150 L O 2 at 500 °C, and additional annealing steps were performed at 500 and 600 °C. Each oxidation and annealing step was studied with STM and STS, and differential conductance maps delivered spatially resolved information on doping and band gap distributions. Initial NiO nucleation and growth begins along the step edges of the Ni−Cr alloy accompanied by the formation of small oxide particles on the terraces. The incubation period known in oxidation of Ni( 100) is absent on Ni−Cr alloy surfaces illustrating the significant changes in surface chemistry triggered by Cr-alloying.Step edge faceting is initiated by oxide decoration along the step edges and is expressed as moirépatterns in the STM images. The surface oxide can be characterized by NiONi(6 × 7) and NiO−Ni(7 × 8) coincidence lattices, which have a cube-on-cube epitaxial relationship. Small patches of NiO are susceptible to reduction during annealing; however, additional oxide coverage stabilizes the NiO. NiO regions are interspersed with areas covered predominantly with a novel cross-type reconstruction, which is interpreted tentatively as a Cr-rich, phase-separated region. Statistical analysis of the geometric features of the surface oxide including step edge heights, and NiO wedge angles illustrates the layer-by-layer growth mode of NiO in this pre-Cabrera−Mott regime, and the restructuring of the alloy−oxide interface during the oxidation process. This experimental approach has offered greater insight into the progression of oxide growth in Ni−Cr thin films and underscores the dramatic impact of alloying on oxidation process in the pre-Cabrera−Mott regime.

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Section: ■ Discussionmentioning

confidence: 99%

From Alloy to Oxide: Capturing the Early Stages of Oxidation on Ni–Cr(100) Alloys

Blades

Reinke

2018

ACS Appl. Mater. Interfaces

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“…Nichrome filaments are also used in certain high temperature oxidizing environments because these alloys are much more resistant to oxidation [8] than pure Ni. In previous studies X-ray photoelectron spectroscopy, Auger electron spectroscopy (AES) and ion scattering spectroscopy (ISS) have been used to investigate the chemical changes that occur during the oxidation of nichrome surfaces [9][10][11]. Apparently, ELS has not been used previously to study nichrome surfaces.…”

Section: Introductionmentioning

confidence: 98%

Electron energy loss spectroscopy study of nickel, chromium and a nickel–chromium alloy

Hagelin-Weaver

Weaver

Hoflund

et al. 2005

Journal of Alloys and Compounds

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“…The original peak at 38 eV is identified in the literature as an M2,3VV Auger transition from clean chromium metal [13]. The peaks at 34, 41, and 48 eV have been previously reported to result from oxidation [14] but there is disagreement about their origins. Whereas Ekelund and Leygraf [3] consider the 34 eV peak to result from chemisorbed oxygen, Palacio et al [10] believe it results from formation of an oxide.…”

Section: I Auger Electron Datamentioning

confidence: 94%

Oxidation of Polycrystalline Chromium between 30°C and 400°C

Thurner

Holloway

1992

Acta Phys. Pol. A

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The formation of coalesced oxide films on atomically clean polycrystalline chromium has been studied with Auger electron spectroscopy and secondary ion mass spectrometry at temperatures between 30°C and 400°C. The data are consistent with an initialed chemisorption of oxygen on the clean Cr followed by nucleation of chromium oxide after 2 L of exposure followed by lateral growth to form a thin, coalesced, saturated oxide film about 0.8 nm thick at 30°C. The saturated oxide was thicker at higher temperatures, being about 80 nm thick at 400°C. Detection of a CrO+ secondary ion was associated witl chemísorbed oxygen, while o ion originated from chromium oxides based upon correlation with chemical changes in the low-energy Auger spectra. Keating of the coalesced oxide caused considerable changes in both the low-energy Auger spectrum as well as the secondary ion emission. Both these as well as time-dependent, reversible changes in secondary ion emission were interpreted as structural rearrangements of the chromium oxide resuhting in relative changes of oxygen either adsorbed on the surface or incorporated into chromium oxide.

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Changes induced at Ni/Cr alloy surfaces by annealing and oxygen exposure

Cited by 24 publications

References 27 publications

From Alloy to Oxide: Capturing the Early Stages of Oxidation on Ni–Cr(100) Alloys

From Alloy to Oxide: Capturing the Early Stages of Oxidation on Ni–Cr(100) Alloys

Electron energy loss spectroscopy study of nickel, chromium and a nickel–chromium alloy

Oxidation of Polycrystalline Chromium between 30°C and 400°C

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