Stability of ultrathin alumina layers on NiAl(110)

Pierce, J. P.; Bartelt, N. C.; Stumpf, R.; McCarty, K. F.

doi:10.1103/physrevb.77.195438

Cited by 21 publications

(17 citation statements)

References 25 publications

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“…A similar behavior was reported for the other systems, i.e., the rhodium oxide on Rh͑111͒, 37 ͱ 5 surface oxide on Pd͑100͒, 38 and the ultrathin aluminum oxide on NiAl͑110͒. 39 We may speculate on the microscopic origin of such kinetic barriers. Further growth of the oxide layer may be limited by two factors: oxygen dissociation, and electron and ion transport through the growing oxide layer and by the diffusion of Ga from the substrate.…”

Section: -35supporting

confidence: 82%

Metastable surface oxide on CoGa(100): Structure and stability

et al. 2010

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We investigated the structure and formation of a surface oxide and bulk ␤-Ga 2 O 3 on CoGa͑100͒ from ultrahigh vacuum to 1 bar oxygen pressure in a temperature range from 300 to 1040 K. We combined in situ surface x-ray diffraction with scanning tunneling microscopy, atomic force microscopy, and density-functional theory calculations. We find that the two-dimensional epitaxial surface oxide layer exhibits a p2mm symmetry with an additional mirror plane as compared to the bulk oxide. The surface oxide layer is found to form under metastable conditions at an oxygen chemical potential ϳ1.6 eV above the stability limit for bulk ␤-Ga 2 O 3 . The formation of the bulk oxide is kinetically hindered by the presence of the oxygen-terminated surface oxide, which most likely hampers dissociative oxygen chemisorption. We observe that below 620 K, the surface oxide is surprisingly stable at 1 bar oxygen pressure. Substrate faceting accompanies the bulk oxide formation at temperatures higher than 1020 K.

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Section: -35supporting

confidence: 82%

Metastable surface oxide on CoGa(100): Structure and stability

et al. 2010

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“…Aluminum oxide thin films have important applications in microelectronics, protective coatings, and catalysis. In particular, the formation of aluminum oxide on NiAl substrates has been studied extensively owing to its important applications in harsh environments ranging from high‐temperature materials in propulsion systems and gas turbine engines to ambient‐temperature reactions, such as surface catalysts and electronic metallization . The aluminum oxides on NiAl(100) were typically formed by directly oxidizing a clean NiAl(100) surface at a high temperature (typically around 727°C or above) or by exposing a clean NiAl(100) surface to oxygen gas at room temperature followed by annealing at a high temperature, both of which would result in fully‐ or partially crystallized oxides .…”

Section: Introductionmentioning

confidence: 99%

“…In particular, the formation of aluminum oxide on NiAl substrates has been studied extensively owing to its important applications in harsh environments ranging from high-temperature materials in propulsion systems and gas turbine engines to ambient-temperature reactions, such as surface catalysts and electronic metallization. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The aluminum oxides on NiAl(100) were typically formed by directly oxidizing a clean NiAl(100) surface at a high temperature (typically around 727°C or above) or by exposing a clean NiAl(100) surface to oxygen gas at room temperature followed by annealing at a high temperature, both of which would result in fully-or partially crystallized oxides. 9,10 Most of the studies focused on investigating the properties of the crystalline oxides due to their stable electronic and geometric structures, with only a few exceptions focusing on the study of amorphous aluminum oxides formed on NiAl(100) substrates.…”

Section: Introductionmentioning

confidence: 99%

The Crystallization of Amorphous Aluminum Oxide Thin Films Grown on NiAl(100)

2014

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The crystallization of amorphous aluminum oxide thin films formed on NiAl(100) has been investigated using in‐situ low energy electron microscopy, low energy electron diffraction, and scanning tunneling microscopy. It is found that both the annealing temperature and annealing time play crucial roles in the crystallization process. A critical temperature range of 450°C–500°C exists for the crystallization to occur within a reasonably short annealing time. The initially uniform oxide film first becomes roughened, followed by coalescing into amorphous‐like oxide islands; further annealing results in the conversion of the amorphous oxide islands into crystalline oxide stripes. The density of the crystalline oxide stripes increases concomitantly with the decrease in the density of the amorphous oxide islands for annealing at a higher temperature or longer time.

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“…A promising approach to real-time studies of dynamic surface processes in TM oxidation [13][14][15][16][17][18] is to employ scat-tering of low-energy electrons in full-field microscopy, also known as low-energy electron microscopy (LEEM).…”

mentioning

confidence: 99%

Self-limited oxide formation in Ni(111) oxidation

et al. 2011

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The oxidation of the Ni(111) surface is studied experimentally with low energy electron microscopy and theoretically by calculating the electron reflectivity for realistic models of the NiO/Ni(111) surface with an ab initio scattering theory. Oxygen exposure at 300 K under ultrahigh-vacuum conditions leads to the formation of a continuous NiO(111)-like film consisting of nanosized domains. At 750 K, we observe the formation of a nano-heterogeneous film composed primarily of NiO (111) surface oxide nuclei, which exhibit virtually the same energy-dependent reflectivity as in the case of 300 K and which are separated by oxygen-free Ni(111) terraces. The scattering theory explains the observed normal incidence reflectivity R(E) of both the clean and the oxidized Ni(111) surface. At low energies R(E) of the oxidized surface is determined by a forbidden gap in the k = 0 projected energy spectrum of the bulk NiO crystal. However, for both low and high temperature oxidation a rapid decrease of the reflectivity in approaching zero kinetic energy is experimentally observed. This feature is shown to characterize the thickness of the oxide layer, suggesting an average oxide thickness of two NiO layers.

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Stability of ultrathin alumina layers on NiAl(110)

Cited by 21 publications

References 25 publications

Metastable surface oxide on CoGa(100): Structure and stability

Metastable surface oxide on CoGa(100): Structure and stability

The Crystallization of Amorphous Aluminum Oxide Thin Films Grown on NiAl(100)

Self-limited oxide formation in Ni(111) oxidation

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