Thermodynamic stability of amorphous oxide films on metals: Application to aluminum oxide films on aluminum substrates

Jeurgens, Lars P. H.; Sloof, W.G.; Tichelaar, F.D.; Mittemeijer, E. J.

doi:10.1103/physrevb.62.4707

Cited by 270 publications

(221 citation statements)

References 35 publications

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“…Extensive tests show that this model accurately represents the ͑0001͒ surface of corundum. The surface relaxation and the surface energy 19 agrees very well with those reported in the literature. 6 Since we are interested in studies of water adsorption at various coverages a larger than primitive supercell has to be used.…”

Section: Methods Of Calculationsupporting

confidence: 81%

The stability of the hydroxylated (0001) surface of α-Al2O3

Łodziana¹,

Nørskov²,

Stoltze

2003

The Journal of Chemical Physics

147

167

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Self-consistent density functional calculations of the hydroxylated ͑0001͒ corundum surfaces are presented. It is demonstrated that the hydroxylated surfaces are the most stable under most, but not all, conditions. Hydroxylation significantly lowers the surface free energy of ␣-alumina. The stability of the hydrated surface resolves the discrepancies between the morphology of the ␣-alumina ͑0001͒ surface observed under ultra-high vacuum, and at ambient conditions. A method for the calculation of the equilibrium surface stoichiometry is proposed. The proposed approach provides a valuable connection between theoretical calculations and experiments with metal oxides.

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Section: Methods Of Calculationsupporting

confidence: 81%

The stability of the hydroxylated (0001) surface of α-Al2O3

Łodziana¹,

Nørskov²,

Stoltze

2003

The Journal of Chemical Physics

147

167

View full text Add to dashboard Cite

show abstract

“…method is therefore important for applied materials science. 24,25 For Cu, the SCLS Z is related to the segregation of Zn ͑the Z + 1 impurity͒ from the bulk to the Cu surface. The ab initio calculations for surface segregation energy of Zn in Cu result in −0.24 eV for Cu ͑111͒ and −0.19 eV for Cu ͑100͒ surfaces, but with an uncertainty up to 0.2 eV.…”

Section: Sclsmentioning

confidence: 99%

A method for the experimental determination of surface photoemission core-level shifts for 3d transition metals

Shamsutdinov

Sloof

Böttger

2005

Journal of Applied Physics

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A method is presented to determine the photoelectron surface core-level shift ͑SCLS͒ of 3d transition metals using x-ray photoelectron spectroscopy. The experimental difficulties arising from the relatively large broadening of photoemission lines in the 3d transition series can be overcome by the analysis of the angular dependence of photoemission spectra. The proposed method has been demonstrated using well-defined single-crystal surfaces of copper. The observed values of the SCLS for copper are compared with those predicted by both ab initio calculations and a macroscopic atom model. The experimental determination of SCLSs opens alternative routes for collecting thermochemical data for surfaces/interfaces.

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“…However, the complexity involved in the oxidation process together with the considerable system size (several hundreds of atoms) have hindered, so far, an atomistic assessment of the CM model. Previous efforts have concentrated on the oxide-metal interface [7][8][9][10][11][12] and initial growth [13][14][15]. In the present Letter, we investigate the underlying atomic and electronic effects that govern the thickness of the protective oxide layer on aluminum from first principles.…”

mentioning

confidence: 99%

Mechanism for Limiting Thickness of Thin Oxide Films on Aluminum

2014

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A first-principles account of the observed limiting thickness of oxide films formed on aluminum during oxidizing conditions is presented. The results uncover enhanced bonding of oxygen to thin alumina films in contact with metallic aluminum that stems from charge transfer between a reconstructed oxide-metal interface and the adsorbed molecules. The first-principles results are compared with the traditional CabreraMott (CM) model, which is a classical continuum model. Within the CM model, charged surface oxygen species and metal ions generate a (Mott) potential that drives oxidation. An apparent limiting thickness is observed as the oxidation rate decreases rapidly with film growth. The present results support experimental estimates of the Mott potential and film thicknesses. In contrast to the CM model, however, the calculations reveal a real limiting thickness that originates from a diminishing oxygen adsorption energy beyond a certain oxide film thickness. Oxidation of metals has tremendous impact on society, and corrosion alone costs the U.S. trillions of dollars each year [1]. Under controlled conditions, however, oxidation plays an important role; thin oxides are used as catalysts, sensors, dielectrics, and corrosion inhibitors. For the latter purpose, metals such as aluminum and rhodium are preferred, as they develop protective oxide layers that inhibit bulk oxidation. Owing to its importance, there have been numerous experimental and theoretical efforts concerning the fundamental understanding of oxidation processes and, especially, the initial growth.The seminal work of Cabrera and Mott (CM) of the mid20th century still remains the key theoretical model for growth of thin oxides on metals, see Fig. 1 [2]. According to CM, electrons from the Fermi level of the metal substrate (ϵ F ) traverse the developing oxide film (with a band gap of E g ) by either tunneling or thermionic emission to acceptor levels (φ a ) of oxygen species, thereby, forming different types of anions (O 2− 2 , O − 2 , O 2− , O − ) on the oxide surface. The negative anions and the positive counterpart at the metal-oxide interface generate an electric potential, called the Mott potential (V M ), which effectively lowers the energy barriers for migration of cations and/or anions through the oxide. This leads to a high oxidation rate even at low temperatures. As the oxide thickness increase, the additional effect of the Mott potential diminishes, and the oxidation process effectively stops at an apparent limiting thickness. It could be noted that although the original CM model discusses charge transfer through tunneling or thermionic emission, the actual transfer is probably defect or polaron mediated. However, this issue is not addressed in the present Letter.Oxidation of aluminum is the prototypical process owing to the simple but versatile electronic structure of aluminum when discussing thin film growth, and this system has played a central role in the establishment of the CM model [3,4]. Recently, Zhou et al. [5,6] showed that the th...

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Thermodynamic stability of amorphous oxide films on metals: Application to aluminum oxide films on aluminum substrates

Cited by 270 publications

References 35 publications

The stability of the hydroxylated (0001) surface of α-Al2O3

The stability of the hydroxylated (0001) surface of α-Al2O3

A method for the experimental determination of surface photoemission core-level shifts for 3d transition metals

Mechanism for Limiting Thickness of Thin Oxide Films on Aluminum

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