Stages Of Cu Oxidation Research Articles

Fundamental Atomic-scale Dynamics of the Initial Stages of Cu Oxidation: Correlating In Situ Environmental Transmission Electron Microscopy with Multi-scale Simulations.

Fundamental Atomic-scale Dynamics of the Initial Stages of Cu Oxidation: Correlating In Situ Environmental Transmission Electron Microscopy with Multi-scale Simulations.

Early and transient stages of Cu oxidation: Atomistic insights from theoretical simulations and in situ experiments

Understanding of metal oxidation is critical to corrosion control, catalysis synthesis, and advanced materials engineering. Although, metal oxidation process is rather complicated, different processes, many of them coupled, are involved from the onset of reaction. Since first introduced, there has been great success in applying heteroepitaxial theory to the oxide growth on a metal surface as demonstrated in the Cu oxidation experiments. In this paper, we review the recent progress in experimental findings on Cu oxidation as well as the advances in the theoretical simulations of the Cu oxidation process. We focus on the effects of defects such as step edges, present on realistic metal surfaces, on the oxide growth dynamics. We show that the surface steps can change the mass transport of both Cu and O atoms during oxide growth, and ultimately lead to the formation of different oxide morphology. We also review the oxidation of Cu alloys and explore the effect of a secondary element to the oxide growth on a Cu surface. From the review of the work on Cu oxidation, we demonstrate the correlation of theoretical simulations at multiple scales with various experimental techniques.

Influence of the surface morphology on the early stages of Cu oxidation

The growth and morphological features of Cu films deposited on NaCl(100) by e-beam evaporation have been examined to evaluate the effect of various surface morphologies on the initial oxidation of Cu. It is shown that epitaxial Cu films with significantly reduced surface roughness can be achieved by first nucleating Cu seeds at 450°C that favors epitaxial Cu grains which is followed by subsequent seed growth at 150°C that favors smooth Cu film. The effect of the variations of the surface morphology of the resulting Cu films by the different growth conditions on the early stages oxidation of Cu films is examined by in situ transmission electron microscopy (TEM) and ex situ atomic force microscopy (AFM). It is shown that the changes in the surface morphologies of the Cu film result in distinct variations in the nucleation density and growth rates of oxide islands. Such correlation between the surface morphology and the initial oxidation behavior of the Cu films provides insights into understanding the microscopic processes of the transient oxidation of metals and for manipulating the initial oxide formation through surface treatments.

The Surface Kinetics of the Initial Oxidation Stages of Cu and Cu Alloys

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

The Low-temperature Initial Oxidation Stages of Cu(100) Investigated by in situ Ultra-high-vacuum Transmission Electron Microscopy

The nucleation and growth of Cu2O islands due to Cu(100) oxidation at temperatures from 200 to 350 °C have been observed by in situ ultra-high-vacuum transmission electron microscopy. For this temperature range, epitaxial Cu2O islands form a triangular shape with rounded edges when Cu(100) is exposed to dry oxygen at 5 × 10−4 Torr in situ. Our initial analysis on the nucleation and growth of these three-dimensional Cu2O islands agrees well with the heteroepitaxial model of surface diffusion of oxygen.

Initial Oxidation Kinetics of Cu(100), (110), and (111) Thin Films Investigated by in Situ Ultra-high-vacuum Transmission Electron Microscopy

The initial oxidation stages of Cu(100), (110), and (111) surfaces have been investigated by using in situ ultra-high-vacuum transmission electron microscopy (TEM) techniques to visualize the nucleation and growth of oxide islands. The kinetic data on the nucleation and growth of oxide islands shows a highly enhanced initial oxidation rate on the Cu(110) surface as compared with Cu(100), and it is found that the dominant mechanism for the nucleation and growth is oxygen surface diffusion in the oxidation of Cu(100) and (110). The oxidation of Cu(111) shows a dramatically different behavior from that of the other two orientations, and the in situ TEM observation reveals that the initial stages of Cu(111) oxidation are dominated by the nucleation of oxide islands at temperatures lower than 550 °C, and are dominated by two-dimensional oxide growth at temperatures higher than 550 °C. This dependence of the oxidation behavior on the crystal orientation and temperature is attributed to the structures of the oxygen-chemisorbed layer, oxygen surface diffusion, surface energy, and the interfacial strain energy.

Effects of surface topology on the formation of oxide islands on Cu surfaces

We examined the effects of surface topology on the nucleation and growth of Cu2O oxide islands during the initial oxidation stages of Cu(100) and Cu(110) surfaces by in situ ultrahigh vacuum transmission electron microscopy and ex situ atomic force microscopy. Our observations indicate that nucleation of three dimensional oxide islands on single crystal surfaces is homogenous, surface defects and dislocations play a very limited role as preferential sites for oxide nucleation. On the other hand, grain boundaries are the preferential sites for oxide nucleation and the oxide islands formed along the grain boundaries show a faster growth rate than that on flat Cu surface. The oxidation on the faceted Cu(110) surface results in heterogeneous nucleation of oxide islands in the facet valleys and one-dimensional growth along the intersection direction of the facets.

Surface Kinetics of Copper Oxidation Investigated by In Situ Ultra-high Vacuum Transmission Electron Microscopy.

We review our studies of the initial oxidation stages of Cu(001) thin films as investigated by in situ ultra-high vacuum transmission electron microscopy. We present our observations of surface reconstruction and the nucleation to coalescence of copper oxide during in situ oxidation in O2. We have proposed a semi-quantitative model, where oxygen surface diffusion is the dominant mechanism of the initial oxidation stages of Cu. We have also investigated the effect of water vapor on copper oxidation. We have observed that the presence of water vapor in the oxidizing atmosphere retards the rate of Cu oxidation and Cu2O is reduced when exposed directly to steam.

Surface Kinetics of Copper Oxidation Investigated by In Situ Ultra-high Vacuum Transmission Electron Microscopy

AbstractWe review our studies of the initial oxidation stages of Cu(001) thin films as investigated by in situ ultra-high vacuum transmission electron microscopy. We present our observations of surface reconstruction and the nucleation to coalescence of copper oxide during in situ oxidation in O2. We have proposed a semi-quantitative model, where oxygen surface diffusion is the dominant mechanism of the initial oxidation stages of Cu. We have also investigated the effect of water vapor on copper oxidation. We have observed that the presence of water vapor in the oxidizing atmosphere retards the rate of Cu oxidation and Cu2O is reduced when exposed directly to steam.

The Limited Role of Surface Defects as Nucleation Sites for Cu2 O on Cu(001)

We have observed the initial oxidation stages of Cu(001) thin films by in situ ultrahigh vacuum‐transmission electron microscopy, examining the role of surface defects, such as surface steps, as possible nucleation sites for the on Cu(001) due to oxidation. Weak beam techniques were used to image surface steps. In contrast to previous speculations, we did not observe evidence that surface steps are preferential nucleation sites. © 1999 The Electrochemical Society. All rights reserved.

Surface Kinetics of the Initial Oxidation Stages of Cu(001) Thin Film, as Studied by In Situ Ultra-High Vacuum Transmission Electron Microscopy

Surface Kinetics of the Initial Oxidation Stages of Cu(001) Thin Film, as Studied by In Situ Ultra-High Vacuum Transmission Electron Microscopy