Temperature dependent early-stage oxidation dynamics of Cu(100) film with faceted holes

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Curnan, Stephen D. House, Wissam A. Saidi, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4743879/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Aug, 2024 Read the published version in High Temperature Corrosion of Materials → Version 1 posted 7 You are reading this latest preprint version Abstract Fundamental understanding of surface oxidation dynamics is critical for rational corrosion protection and advanced manufacturing of nanostructured oxides. In situ Environmental TEM (ETEM) provides high spatial (nano- to atomic- scale) and temporal (< 0.1 second) resolution to investigate the early-stage oxidation/corrosion dynamics of metals and alloys. Thin samples with facets are widely used to enable cross-sectional observation of the oxidation dynamics in ETEM. However, how different facet orientations oxidize under the same conditions, and how these facets change the oxidation process, has not been investigated before. Using in situ ETEM, we systematically compare the oxidation dynamics of Cu(001) thin films, with faceted holes exposing {100} and {110} facets at temperatures ranging from 250–600 ˚C under 0.03 Pa O 2 . Oxidation preference is observed to change, from Cu(110) facets at lower temperatures to Cu(100) facets at ~ 500 ˚C. Oxide growth mechanisms change from outward growth on Cu 2 O surfaces at low temperatures, to inward growth on Cu-Cu 2 O interfaces at high temperatures. At high temperatures (500–600 ˚C), a rod-like Cu 2 O morphology is observed, with side facets of ~{024} and top facets of {100} on Cu(100). This differs from the square-shaped Cu 2 O exposing {110} facets formed on Cu(001) surfaces. Rod-like oxides exhibit directional growth along their lengths with linear growth rates, regardless of rod length and width. This suggests that O from Cu(001) surfaces, rather than Cu(100) facets, serves as an O source for oxide growth. These results show a direct comparison of oxidation at different orientations with temperature, underscoring the temperature dependence of oxidation preference. Our results also suggest future in situ ETEM experiments viewing oxidation corrosion cross-sectionally should be cautious when oxide size is comparable with sample thickness, as the oxidizing mechanism may change due to sample thickness. in situ environmental TEM oxidation facets holes Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Characterizing surface oxidation processes at the nano- to atomic- scale is critical for fundamentally understanding corrosion, as well as providing guidance to rational catalyst design and advanced manufacturing of oxide heterostructures. Metal oxidation generally adheres to the following sequence: oxygen chemisorption and reconstruction, oxide nucleation and growth, and bulk oxidation.[1] The oxygen chemisorption stage has been extensively investigated by surface science methods such as scanning tunneling microscopy (STM), which examines the structures of metal surfaces, such as surface reconstructions, with up to ~ 1 monolayer of absorbed gases[2–4]. On the other hand, the bulk oxidation stage – which focuses on the growth of continuous oxide scales – has also been widely investigated using methods such as thermogravimetric analysis (TGA), which shows oxide film growth kinetics follows parabolic, logarithmic, or other kinetic mechanisms[5–9]. However, the microstructural evolution during oxide nucleation and growth is poorly understood. Although surface science approaches have resolved different surface structures[2–4] and how to tune the surface reconstructions using factors such as stress[10–14], how these surface reconstructions impact oxide nucleation and growth is unclear. Existing bulk oxidation theories, such as Cabrera-Mott theory[5] or Wagner theory[7], assume a uniform oxide layer and do not consider the effects of microstructure on oxidation. For example, by comparing the diffusivity of metal ( d M ) and oxygen ( d O ) through the oxide, the oxidation can be divided into inward oxidation ( d M d O , metal diffuses through the oxide layer, oxidation happen at oxide surfaces) [15]. However, microstructural features such as orientation, defects, and holes can change the diffusion process, but are not considered in classical oxidation theories. Moreover, for nanostructured oxides, metal or oxygen do not necessarily need to diffuse through the oxide[16]. Hence, although these bulk oxidation theories are still widely used to guide oxide growth, they are less accurate in guiding the growth of nanostructured oxides. The development of Environmental Transmission Electron Microscopy (ETEM) has enabled real-time observation of gas-solid reactions at the nano-to-atomic scale, which provides a new direction to understanding the oxidation dynamics. However, TEM requires a thin sample thickness (typically < 100 nm); how this thickness difference impacts oxidation dynamics is worth investigating. As a widely used model material for oxidation, Cu oxidation at different conditions has been systematically investigated in previous research using various techniques including ETEM[17–19]. However, previous ETEM studies on Cu thin film oxidation are focused on the oxide morphology of flat Cu surfaces.[17–19] Direct comparison of how different orientations oxidize under identical condition is lacking, as ensuring local temperature, oxygen concentration, and oxidation time are consistent is experimentally challenging. Moreover, as oxide islands grow on Cu surfaces, under TEM the electron beam passes through both oxides and Cu, which makes it difficult to identify and characterize small oxides when they nucleate. Recently, by using thin films with holes or using Focused Ion Beam or focused electron beam to create facets/holes on the sample, oxidation processes from the cross-sectional view can be carried out on these facets[16,20–26]. This provides a much higher spatial resolution to observe oxidation dynamics at the atomic scale, such as surface reconstruction formation[25], interface dislocation propagation[20,27], and oxide growth kinetics[16]. However, these holes or facets can introduce many significant factors impacting oxidation, such as orientations, steps, and edges[26,28,29]. How these holes/facets change oxidation outcomes, and how well oxidation on the facets replicates oxidation of the bulk, is unclear. In this work, we performed in situ ETEM oxidation experiments on Cu thin films with faceted holes exposing Cu(100) and (110) facets at different temperatures, to directly compare oxidation dynamics on different facet orientations with flat surfaces. Material and Methods Single-crystalline Cu(100) thin film samples with a thickness of 60 nm were grown on a NaCl(100) substrate using an ultra-high-vacuum (UHV) e -beam evaporator at 300 ˚C[16]. The films were transferred to TEM Cu mesh grids using the float-off method[16] by dissolving the NaCl substrate in ultra-pure water. The sample was cleaned by float-off in fresh ultra-pure water for several times to remove residual NaCl. In situ ETEM experiments were carried out on these thin film samples using a dedicated differentially pumped environmental TEM (Hitachi H-9500 ETEM) operating at 300 keV with a home-built gas delivery system with gas up to 0.1 Pa. A double-tilt furnace-type heating holder (Hitachi) was used to apply and control the temperature up to 800 ˚C. The sample temperature was calibrated with fixed melting-point samples to ensure accurate temperature measurement. To avoid contamination impacting the oxidation result, the ETEM chamber was baked out before each oxidation experiment, the holder was plasma cleaned before each experiment, and the samples were freshly grown before each ETEM experiment. As-grown Cu thin films are continuous single crystalline films, with small holes resulting from film thickness (~ 60 nm). Due to unavoidable air exposure during transferring as-grown samples from the evaporator chamber to the TEM (~ 30 min), as-grown thin films are slightly oxidized, forming small few-nanometer sized nano-oxide islands. In situ ETEM experiments start with annealing these thin films in 0.1 Pa H 2 under ~ 600 ˚C to reduce native oxides on the film. This hydrogen annealing process also creates larger (~ hundred nm) faceted holes exposing Cu(100) and (110) facets on the thin film, as well as remove defects such as dislocations on the sample, as shown in Fig. 1 . Since holes expand quickly at higher temperatures and can cause films to break, 600 ˚C was chosen as the maximum temperature for oxidation of Cu films with holes. In situ oxidation experiments were then performed under O 2 , varying temperature (200–600 ˚C) and pressure. Results and discussion Oxidation at low temperature (200–350 ˚C) Under low temperatures (200–350 ˚C), small (< 10 nm) oxide islands were observed to form on the faceted holes. The oxide islands are similar to native oxides on Cu films formed at room temperature. Using in situ ETEM, the nucleation sequence of nano-islands on different facets is characterized. Due to the low temperature, the oxidation speed is much lower at the same oxidizing pressure. For example, at 250 ˚C under 0.03 Pa O 2 , it took two hours of oxygen exposure until oxide nano-islands were observed. To accelerate the oxidation process, higher oxygen pressure (0.1 Pa) was used at low temperatures. This reduced the amount of time needed to form observable oxides to tens of minutes. As shown in Fig. 1 , oxide islands were first observed on Cu(110) facets at 250˚C under 0.1 Pa O 2 (Fig. 1 a-b), then they were seen on Cu(100) facets (Fig. 1 c). The time sequence over which each oxide island formed is plotted in Fig. 1 d, which shows a clear trend of oxide nucleation preference on Cu(110) facets over Cu(100) facets. During this process depicted in Fig. 1 e-f, oxide nano-islands are mainly observed along the hole, rather than on the flat surface. They mostly demonstrate outward oxidation behavior, that is, oxide growth on oxide surfaces without significantly changing the underlying metal surfaces. These results indicate diffusing Cu atoms near the holes are the major Cu source for oxides during this stage. This is consistent with our previous HRTEM observation of oxide growth at a similar condition (300 ˚C, 0.03 Pa O 2 )[16], which shows layer-by-layer oxide growth on the Cu 2 O surface. Such growth occurs without consumption of the metal substrate under the oxide island, until surface diffusing Cu atoms are depleted. During the early oxidation, oxide nano-islands were only observed near the holes (Fig. 1 e-f). After a longer oxidation time (Fig. 1 g), oxide nano-islands were observed on Cu(001) thin film surfaces. Selected area electron diffraction (SAED) patterns (Fig. 1 h) show Cu 2 O nano-islands follow cube-on-cube epitaxy with Cu(001) substrates. Oxide islands on Cu surfaces demonstrate homogenous, uniform distributions along surfaces, similar to previous experimental observations on flat Cu surfaces [17,18,21]. Over this temperature range, an oxidation preference sequence of Cu(110) facet > Cu(100) facet > > Cu(001) flat surface is resolved. Thus, holes can significantly accelerate oxidation by introducing edges, preferable facet orientations, and free Cu atoms diffusing on surfaces. Oxidation at medium temperature (350–450 ˚C) Under a medium temperature range (350–450 ˚C), larger oxides (~ 100 nm in at least one dimension) are observed to form along Cu(110) facets (Fig. 2 ). As shown in Fig. 2 a, needle-shaped oxides were observed to nucleate on Cu(110) facets at 350 ˚C. As depicted by the oxide on the rightward (110) facet, nucleating Cu 2 O initially occurs only on {100} facets, growing in both width and height while maintaining its triangular shape. When the height of the oxide reached ~ 15 nm, a {110} interface formed at its bottom. This resulted in a trapezoid-shaped oxide with {100} side facets and {110} bottom facets (Fig. 2 b). Then, this oxide grew mainly along its width, while its height remained almost constant. Both high-resolution (HRTEM) image (Fig. 2 b) and the SAED pattern (Fig. 2 c) suggest Cu 2 O islands formed under this condition also share cube-on-cube epitaxy with the Cu substrate. In contrast, few oxides were observed to nucleate on Cu(100) facets. Oxides nucleating on Cu(100) facets are observed only on larger holes (Cu(100) facet > 100 nm), not on smaller holes. This is probably due to the fact that on smaller holes the distances between oxides -- from oxides that first nucleate on Cu(110) and oxides that will subsequently nucleate on the Cu(100) facets -- are insufficient for the average oxide distance under this condition. Only larger holes with large Cu(100) facets can provide enough space for the widely spaced nucleating oxides. On the Cu(001) flat surface, right-triangle-shaped Cu 2 O are observed (Fig. 2 d). They feature {100} short edges and {110} long edges, respectively marked by dashed red and blue lines. These triangular-shaped oxide islands are consistent with previous literature reports on uniform Cu thin films.[17,30] At 450˚C, oxides are also observed to nucleate on Cu(110) facets first (Fig. 2 e), forming rectangular-shaped oxides with {110} facets. On flat Cu(001) surfaces, right-triangular-shaped Cu 2 O islands are also observed, exposing {100} short edges and {110} long edges (Fig. 2 f). Compared with outcomes at 350 ˚C, oxide densities decrease and average oxide distances increase, while larger oxide islands were observed after the same oxidation time. Under this temperature range, oxide formation follows the sequence of Cu{110} facet > Cu{100} facet ≥ Cu(001) surface. Oxides grown on facets show both inward and outward oxidation, that is, oxides grow both on the metal-oxide interface and on the oxide surface. These results indicate that under these conditions, Cu atoms from facets are the main Cu source for Cu 2 O growth on holes. During the oxidation process, O from faceted holes serves as the main O source for Cu 2 O, such that O needs to diffuse through the oxide to form new Cu 2 O. This leads to self-limiting oxidation in the depth direction , which forms observed needle-shaped islands on Cu(110) facets. Oxidation at high temperatures (500–600˚C) Under high temperatures (500–600 ˚C), oxide islands form much faster and grow into larger and more faceted shapes. Unlike lower temperatures that prefer nucleation at Cu(110) facets, oxides at high temperatures prefer to nucleate at Cu(100) facets (Fig. 3 ). At 500 ˚C, a mixture of oxides nucleating on both Cu(100) and Cu(110) facets are observed, indicating that their nucleation preferences are similar (Fig. 3 a). Oxides nucleating on Cu(110) facets feature {100} (red) and {110} (blue) interfaces, similar to those formed in the medium-temperature range. However, the oxides grown on Cu(100) facets show a directional growth into Cu substrates along the direction, forming rods. The sides of the rods are oriented along {024} facets (green). At 550 ˚C and 600 ˚C, oxides are only observed to nucleate on Cu(100) facets (Fig. 3 b-e, Fig. 5 c). These oxides feature higher index facets like {024} (green), and lower index facets such as {100} (red) and {110} (blue). As shown in Fig. 3 c-e, the metal-oxide interfaces along the and directions grow much faster than along the directions. This is evidenced by the size evolution of the oxide, and the consumption of Cu near the Cu 2 O||Cu{100} interface, as the originally faceted hole (dashed line) became concave. As shown in Fig. 3 f, oxide nucleation on Cu(100) facets requires a relatively large Cu(100) facet. When the Cu(100) facet is too small, Cu 2 O is observed to form only on Cu(001) surfaces, forming square-shaped islands exposing {110} facets. This oxide shape on flat surfaces is consistent with previous literature reports at this temperature.[17] Oxides forming on flat surfaces show random distributions, regardless of their relative distances from holes. This result indicates oxide nucleation on Cu(001) surfaces is preferred over that on Cu(110) facets at high temperatures. After prolonged oxidation, all holes with Cu(100) facets are oxidized, forming zig-zag shaped oxide rods bending at holes (Fig. 4 a-c). The rods show side facets along {013} (yellow), {024} (green), or {015} (purple) orientations, and a top facet along {010} (red). As shown in Fig. 4 , the oxide grows mainly in the length direction (along ), while the width of the rods maintains almost unchanged. This is similar to the observation in Fig. 3 b-d, indicating the Cu 2 O||Cu direction is the preferred oxide growth direction. Figure 4 d plots each actual oxide rod length between {020} rod tip and the nearest hole facet, while Fig. 4 e measures the relative length changes from Fig. 4 (a). Both lengths are measured along the direction perpendicular to the rod tip surface ({020}, as illustrated in Fig. 4 c. Figure 4 e confirms the growth rates of each rod are similar (3.8 ± 0.5 nm/min), following a quasi-linear relationship with time regardless of the initial length (Fig. 4 d), width, or side facet orientation of each rod. This result indicates that the O source for Cu 2 O rod growth is coming from absorbed O on Cu film surfaces, instead of O on holes that needs to diffuse through the oxide. Because if the latter case was true, growth rate would decrease with increasing oxide thickness. Hence, in this high-temperature range (500–600 ˚C), the oxidation preference sequence follows Cu(100) facet > Cu(001) surface > > Cu(110) facet. The oxidation of Cu(100) faceted holes demonstrates inward oxidation, that is, oxide growth into metal, without expanding on the original metal surface. O on the Cu surface serves as the O source for Cu 2 O growth rather than O from the faceted hole, which was observed at medium and low temperatures. Summary and Outlooks In summary, we systematically investigated the oxidation of Cu(100) thin films with faceted holes along Cu{100} and Cu{110} under 0.03 Pa O 2 between temperatures 200 and 650°C at a temperature interval of 50°C. The oxide morphology and formation sequence changed with increasing temperature as summarized below and in Fig. 5 : At low temperature (200–300°C, Fig. 5 a,d), high densities of Cu(100) facet > Cu(001) surface. Outward oxidation is noted, indicating that diffusing Cu near faceted holes is the source of Cu during oxide formation. At medium temperature (350–450°C, Fig. 5 b,e), needle-shaped Cu 2 O islands were observed on Cu(110) facets. Right-triangular-shaped Cu 2 O islands were observed on flat surfaces with short edges along Cu{100}, and long edges along Cu{110} directions. Oxidation preference follows the order of Cu(110) facet > Cu(100) facet ≥ Cu(001) surface. Oxidation is observed to grow both inward and outward on Cu(110) facets, and oxide growth shows self-limiting growth perpendicular to the Cu(110) facet. These observations indicate that Cu and O from these facets are the sources of Cu and O during oxide formation. At high temperature (500–600°C, Fig. 5 c,f), the oxidation preference changed to Cu(100) facet > Cu(001) surface > > Cu(110) facet. Faceted rod-like oxides were observed on Cu(100) facets, with side surfaces of ~{240} planes, and top surfaces of {100} planes. Rod-like oxides mainly grow inward at Cu 2 O|Cu(100) interfaces, with quasi-linear growth rates regardless of distance from their nearest hole facets. This indicates oxygen from Cu(001) surfaces is the O source for oxide growth on Cu(100) facets. Our results directly compare the oxidation preference and dynamics of different orientations under identical conditions (temperature, pressure, oxidation time, purity, etc ). It was previously believed that Cu(110) oxidation is preferred over that on Cu(100) due to easier O diffusion on reconstructed Cu(110) surfaces.[19] However, we observe the change of preferred oxidation orientation from Cu(110) to Cu(100) over a critical temperature of 500°C. The mechanism for this switch at higher temperature might be a change in lattice mismatch (strain) over temperature, or associated surface stresses. Previous research on CuAu alloy oxidation showed faster oxide nucleation and growth rates with increased Au composition due to reduced interfacial strain[17,26,31], indicating the oxide nucleation and growth rate can be tuned by interfacial strain. At different oxidation temperature as shown in this paper, due to the different thermal expansion of different Cu and Cu 2 O orientations, the interfacial strain changes, which might lead to the observed switch in oxidation facet preference. Alternatively, changes in relative ordering of O adsorption over different facets, or surface structure changes from processes such as reconstruction, may also induce this switch. Given prior work on defects such as surface steps and edges[16,25,29,32,33], changes in surface structures impacting oxidative preferences can also affect corresponding switching. In-depth mechanistic explanation of this phenomenon requires further theoretical simulations and higher resolution experimental investigations, which require in situ experiments at higher time resolution and more stable heating stages under higher temperatures. Moreover, our results also highlight that inward oxidation (growth at metal-oxide interface) or outward oxidation (growth at oxide surface) behavior, which was considered to be constant for a given material, can be changed by adjusting temperature and/or Cu and O sources. These findings unveil a promising avenue for manipulating oxide structure. This also provides a caveat for future in situ TEM studies on oxidation: as sample thickness reduces, metal or oxygen sources can differ from those of bulk. This may vary oxidation outcomes versus those of bulk, especially when oxide size is comparable to that of sample thickness. These experiments systematically compare oxidation behaviors by solely changing temperature, while keeping other reaction conditions constant. Such controlled experiments show differences in oxide morphologies, oxide growth mechanism, and orientation preferences. These differences reveal complexity in the metal oxidation process. By changing temperature, many important oxidation steps – such as oxygen chemisorption, oxygen and/or metal diffusion, and oxide growth mechanisms – can change. Hence, more systematic and concerted experimental and theoretical investigations are needed to gain a more comprehensive understanding of early-stage oxidation, which will guide the advanced fabrication and engineering of nano-oxides. Declarations Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Author Contribution J.C.Y. and W.A.S. conceived and directed the project. M.L. conducted the experiments, data analysis, and drafted the manuscript. M.T.C. conducted D.F.T. simulations. S.H. contributed to data analysis. All authors contributed to results discussion and manuscript refinement. Acknowledgement The authors acknowledge the funding support from NSF grants DMR-1410055, DMR-1508417, DMR-1410335, CBET-2130804 and CMMI-1905647, as well as support from Hitachi High Technologies and technical assistance from the Nanoscale Fabrication and Characterization Facility (NFCF) in the Petersen Institute of Nano Science and Engineering (PINSE) at the University of Pittsburgh. This research used Electron Microscopy resources of the Center for Functional Nanomaterials (CFN), which is a U.S. Department of Energy Office of Science User Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government. Data Availability Data is provided within the manuscript. References Gattinoni C, Michaelides A. Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides. Surface Science Reports . 2015;70:424-447. Jensen F, Besenbacher F, Laegsgaard E, Stensgaard II. Surface reconstruction of Cu(110) induced by oxygen chemisorption. 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Journal of Physical Chemistry C . 2017;121:11251-11260. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 01 Aug, 2024 Read the published version in High Temperature Corrosion of Materials → Version 1 posted Editorial decision: Accepted 20 Jul, 2024 Reviews received at journal 18 Jul, 2024 Reviewers agreed at journal 18 Jul, 2024 Reviewers invited by journal 16 Jul, 2024 Editor assigned by journal 16 Jul, 2024 Submission checks completed at journal 16 Jul, 2024 First submitted to journal 15 Jul, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4743879","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":329597359,"identity":"f51f06bf-05b5-4791-a297-b613f9811a2a","order_by":0,"name":"Meng Li","email":"","orcid":"","institution":"Brookhaven National Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Meng","middleName":"","lastName":"Li","suffix":""},{"id":329597360,"identity":"7af5e944-46c7-42f3-b1c5-7dd5bceedc33","order_by":1,"name":"Matthew T. Curnan","email":"","orcid":"","institution":"Korea Institute of Energy Technology (KENTECH)","correspondingAuthor":false,"prefix":"","firstName":"Matthew","middleName":"T.","lastName":"Curnan","suffix":""},{"id":329597361,"identity":"8eb070b0-5bff-436f-becb-8b2a49ddfcd0","order_by":2,"name":"Stephen D. House","email":"","orcid":"","institution":"Sandia National Laboratories","correspondingAuthor":false,"prefix":"","firstName":"Stephen","middleName":"D.","lastName":"House","suffix":""},{"id":329597362,"identity":"c97624b8-a51b-480e-9cb9-d5fc8f098ac2","order_by":3,"name":"Wissam A. Saidi","email":"","orcid":"","institution":"National Energy Technology Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Wissam","middleName":"A.","lastName":"Saidi","suffix":""},{"id":329597363,"identity":"19bb6e20-88b6-46d2-926d-cdb6d9604a28","order_by":4,"name":"Judith C. Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuElEQVRIiWNgGAWjYBACxgYQaWCTwMBOmpaCtAQGZtLs+nCYBC3MM5KfPfxicD7PnJmB+cXHNmIcNiPN3FjG4HaxZTMDm+VM4rQkmElLGNxO3HCYgc2Y5wxRWtK/AbWcI0lLjpnkB4MDIC3Mj3kqiNHS86ZMmsEgudjgMGMb4wxitBi2p2+T/PHHLs/gePPhDx8MiNEyARgjPBAL2ySI0MDAIM9/gIHxB4TN/IEoLaNgFIyCUTDiAAAKQDbz9TosVAAAAABJRU5ErkJggg==","orcid":"","institution":"Brookhaven National Laboratory","correspondingAuthor":true,"prefix":"","firstName":"Judith","middleName":"C.","lastName":"Yang","suffix":""}],"badges":[],"createdAt":"2024-07-15 15:22:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4743879/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4743879/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11085-024-10274-7","type":"published","date":"2024-08-01T15:57:53+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":62096988,"identity":"5d17eced-9801-4639-a22d-598becde1eeb","added_by":"auto","created_at":"2024-08-09 08:55:00","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1530950,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eIn situ\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e ETEM observation of oxide nucleation on Cu(100) film with faceted hole at 250 ˚C under 0.1 Pa O\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e.\u003c/strong\u003e \u003cstrong\u003e(a-c)\u003c/strong\u003e BF-TEM images on the same hole shows Cu\u003csub\u003e2\u003c/sub\u003eO nano-islands \u003cstrong\u003e(b)\u003c/strong\u003e nucleate on Cu(110) facets first, \u003cstrong\u003e(c)\u003c/strong\u003e then on Cu(100) facets. \u003cstrong\u003e(d)\u003c/strong\u003e Plot of time when a new oxide island is observed on each facet. \u003cstrong\u003e(e-g)\u003c/strong\u003e Oxidation under a longer time at a smaller magnification on the same sample with the \u003cem\u003ee\u003c/em\u003e-beam off. \u003cstrong\u003e(e)\u003c/strong\u003e BF-TEM image on a different hole that was not exposed to the \u003cem\u003ee\u003c/em\u003e-beam before shows continued growth of the oxide nano-islands on Cu(110) and Cu(100) facets. \u003cstrong\u003e(f)\u003c/strong\u003e Dark-field TEM (DF-TEM) image (on Cu\u003csub\u003e2\u003c/sub\u003eO(110) diffraction spot) of (e) showing oxides are mainly formed around the holes. \u003cstrong\u003e(g)\u003c/strong\u003e DF-TEM image of a different hole that shows Cu\u003csub\u003e2\u003c/sub\u003eO nano-islands form on Cu(100) surfaces at ~35 min. \u003cstrong\u003e(h) \u003c/strong\u003eElectron diffraction pattern of the sample (contrast inverted and enhanced) showing oxides follow cube-on-cube epitaxy with Cu. The satellite diffraction patterns around Cu diffraction spots (blue) are due to multiple diffraction events, in which electrons pass through both Cu\u003csub\u003e2\u003c/sub\u003eO and Cu.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4743879/v1/ec531918fa62d7a30752290c.png"},{"id":62096987,"identity":"a5f4a887-9992-404f-b7d3-84f69839b595","added_by":"auto","created_at":"2024-08-09 08:54:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2535652,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eOxide formation at medium temperature (350-450 °C) under 0.03 Pa O\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e. (a)\u003c/strong\u003e Bright-field TEM (BFTEM) image of oxide morphology at 350 °C on faceted hole. \u003cstrong\u003e(b)\u003c/strong\u003e High-Resolution TEM (HRTEM) image of the Cu\u003csub\u003e2\u003c/sub\u003eO island in the boxed region in (a). A trapezoidal shaped oxide island is observed with {100} side facets and {110} bottom facet on Cu(110). \u003cstrong\u003e(c)\u003c/strong\u003e Corresponding electron diffraction pattern (contrast inverted) of the sample shows Cu\u003csub\u003e2\u003c/sub\u003eO follows cube-on-cube epitaxy with Cu. \u003cstrong\u003e(d)\u003c/strong\u003e BFTEM image of oxide morphology at 350˚C on flat surface. \u003cstrong\u003e(e-f)\u003c/strong\u003e BFTEM image of oxide morphology at 450˚C on \u003cstrong\u003e(e)\u003c/strong\u003e faceted hole and \u003cstrong\u003e(f)\u003c/strong\u003e flat surface. {100} and {110} facets are outlined in red and blue, respectively.\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4743879/v1/2866769b3ae09b81daebde72.png"},{"id":62097621,"identity":"d61dd221-2dd6-4450-8332-1d5b58558ab0","added_by":"auto","created_at":"2024-08-09 09:03:00","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1081809,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCu oxidation at high temperature under 0.03 Pa O\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e. \u003c/strong\u003e(a) At 500˚C, Cu\u003csub\u003e2\u003c/sub\u003eO is observed to nucleate on both Cu(100) and (110) facets. (b-e) At 550˚C, Cu\u003csub\u003e2\u003c/sub\u003eO is only observed to form on Cu(100) facets. Oxides feature {024} (green), {110} (blue), and {100} (red) facets. The dashed line in (c-f) shows the original shape of the hole. With oxide growth, Cu on Cu(110) edges diffused to Cu\u003csub\u003e2\u003c/sub\u003eO, making the originally flat facet concave. (f) When the Cu(100) facet is too small, Cu\u003csub\u003e2\u003c/sub\u003eO will not form on holes. Square-shaped Cu\u003csub\u003e2\u003c/sub\u003eO islands exposing {110} facets were observed on Cu(001) flat surfaces.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4743879/v1/059118152ed4e4bd21281aff.png"},{"id":62096991,"identity":"3d927ecf-a98b-4193-9880-39c72e4a500e","added_by":"auto","created_at":"2024-08-09 08:55:00","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1021998,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eIn situ\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e ETEM observation of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eO growth dynamics on holes at 550˚C under 0.03 Pa O\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e. \u003cstrong\u003e(a-c) \u003c/strong\u003eTime sequence of oxides grown on Cu; the time on each image shows the duration after O\u003csub\u003e2\u003c/sub\u003e is introduced. Rod-like oxides have {013} (yellow), {024} (green), and {015} (purple) side facets, and {002} (red) top facets. Oxides grow mainly along the \u0026lt;001\u0026gt; direction, while the widths of rods remain almost unchanged until \u003cstrong\u003e(c) \u003c/strong\u003etwo rods from two nearby holes connect. \u003cstrong\u003e(d) \u003c/strong\u003ePlot of actual length of each {002} facet from the hole along the \u0026lt;001\u0026gt; direction, marked by the \u003cem\u003el\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e arrow in (c). \u003cstrong\u003e(e)\u003c/strong\u003e Plot of relative length change of each {002} facet from (a) along the \u0026lt;001\u0026gt; direction, marked by the \u003cem\u003el\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e arrow in (c). Growth rates are quasi-linear, with a similar growth rate for each facet regardless of its original length from the hole. \u003cstrong\u003e(f)\u003c/strong\u003e Corresponding electron diffraction pattern (contrast inverted) shows Cu\u003csub\u003e2\u003c/sub\u003eO follows cube-on-cube epitaxy with Cu. Cu and Cu\u003csub\u003e2\u003c/sub\u003eO diffraction spots are labeled with blue and red, respectively.\u0026nbsp;\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-4743879/v1/4da76e9b66d9db6c47394bbe.png"},{"id":62096990,"identity":"8524df9f-ae09-4578-a945-d53f8fb3514c","added_by":"auto","created_at":"2024-08-09 08:55:00","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":556979,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTransition of Cu\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eO island morphologies and nucleation facets with temperature. \u003c/strong\u003e(\u003cstrong\u003ea\u003c/strong\u003e)~(\u003cstrong\u003ec\u003c/strong\u003e) Bright field TEM (BF-TEM) images of Cu(100) films (black) with faceted holes (white) after oxidation. Cu\u003csub\u003e2\u003c/sub\u003eO are lighter grey areas marked by arrows. (\u003cstrong\u003ed\u003c/strong\u003e)~(\u003cstrong\u003ef\u003c/strong\u003e) Corresponding schematic of the shape and distribution of oxide islands (orange) on facets and flat film terraces (grey) in (a)~(c). (\u003cstrong\u003ea\u003c/strong\u003e) At low oxidation temperatures (200-300 ℃), small Cu\u003csub\u003e2\u003c/sub\u003eO islands (indicated by arrows) with an average diameter \u003cem\u003ed\u003c/em\u003e \u0026lt; 5 nm form preferentially on Cu{110} facets. (\u003cstrong\u003eb\u003c/strong\u003e) At medium oxidation temperatures (350~450 ℃), large lath-shaped Cu\u003csub\u003e2\u003c/sub\u003eO islands, with lengths of ~100 nm and widths of 15 nm, form along Cu{110} facets. (\u003cstrong\u003ec\u003c/strong\u003e) At high oxidation temperatures (500~600 ℃), large faceted Cu\u003csub\u003e2\u003c/sub\u003eO form on Cu{100} facets, with respective side and top facet orientations of {024} and {001} forming Cu\u003csub\u003e2\u003c/sub\u003eO/Cu interfaces. The faceted Cu\u003csub\u003e2\u003c/sub\u003eO island can grow up to a micrometer size scale.\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-4743879/v1/f0104082a62282f77bcb5ffb.png"},{"id":62097622,"identity":"15281b33-1916-4fd9-9d41-da0b4302734b","added_by":"auto","created_at":"2024-08-09 09:03:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8359032,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4743879/v1/4a15780d-aacb-46ce-9a33-57019c619a3e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Temperature dependent early-stage oxidation dynamics of Cu(100) film with faceted holes","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCharacterizing surface oxidation processes at the nano- to atomic- scale is critical for fundamentally understanding corrosion, as well as providing guidance to rational catalyst design and advanced manufacturing of oxide heterostructures. Metal oxidation generally adheres to the following sequence: oxygen chemisorption and reconstruction, oxide nucleation and growth, and bulk oxidation.[1] The oxygen chemisorption stage has been extensively investigated by surface science methods such as scanning tunneling microscopy (STM), which examines the structures of metal surfaces, such as surface reconstructions, with up to ~\u0026thinsp;1 monolayer of absorbed gases[2\u0026ndash;4]. On the other hand, the bulk oxidation stage \u0026ndash; which focuses on the growth of continuous oxide scales \u0026ndash; has also been widely investigated using methods such as thermogravimetric analysis (TGA), which shows oxide film growth kinetics follows parabolic, logarithmic, or other kinetic mechanisms[5\u0026ndash;9]. However, the microstructural evolution during oxide nucleation and growth is poorly understood. Although surface science approaches have resolved different surface structures[2\u0026ndash;4] and how to tune the surface reconstructions using factors such as stress[10\u0026ndash;14], how these surface reconstructions impact oxide nucleation and growth is unclear. Existing bulk oxidation theories, such as Cabrera-Mott theory[5] or Wagner theory[7], assume a uniform oxide layer and do not consider the effects of microstructure on oxidation. For example, by comparing the diffusivity of metal (\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eM\u003c/em\u003e\u003c/sub\u003e) and oxygen (\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eO\u003c/em\u003e\u003c/sub\u003e) through the oxide, the oxidation can be divided into inward oxidation (\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eM\u003c/em\u003e\u003c/sub\u003e\u0026lt;\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eO\u003c/em\u003e\u003c/sub\u003e, oxygen diffuses through the oxide layer, oxidation happen at metal-oxide interfaces), and outward oxidation (\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eM\u003c/em\u003e\u003c/sub\u003e\u0026gt;\u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eO\u003c/em\u003e\u003c/sub\u003e, metal diffuses through the oxide layer, oxidation happen at oxide surfaces) [15]. However, microstructural features such as orientation, defects, and holes can change the diffusion process, but are not considered in classical oxidation theories. Moreover, for nanostructured oxides, metal or oxygen do not necessarily need to diffuse through the oxide[16]. Hence, although these bulk oxidation theories are still widely used to guide oxide growth, they are less accurate in guiding the growth of nanostructured oxides.\u003c/p\u003e \u003cp\u003eThe development of Environmental Transmission Electron Microscopy (ETEM) has enabled real-time observation of gas-solid reactions at the nano-to-atomic scale, which provides a new direction to understanding the oxidation dynamics. However, TEM requires a thin sample thickness (typically\u0026thinsp;\u0026lt;\u0026thinsp;100 nm); how this thickness difference impacts oxidation dynamics is worth investigating. As a widely used model material for oxidation, Cu oxidation at different conditions has been systematically investigated in previous research using various techniques including ETEM[17\u0026ndash;19]. However, previous ETEM studies on Cu thin film oxidation are focused on the oxide morphology of flat Cu surfaces.[17\u0026ndash;19] Direct comparison of how different orientations oxidize under identical condition is lacking, as ensuring local temperature, oxygen concentration, and oxidation time are consistent is experimentally challenging. Moreover, as oxide islands grow on Cu surfaces, under TEM the electron beam passes through both oxides and Cu, which makes it difficult to identify and characterize small oxides when they nucleate. Recently, by using thin films with holes or using Focused Ion Beam or focused electron beam to create facets/holes on the sample, oxidation processes from the cross-sectional view can be carried out on these facets[16,20\u0026ndash;26]. This provides a much higher spatial resolution to observe oxidation dynamics at the atomic scale, such as surface reconstruction formation[25], interface dislocation propagation[20,27], and oxide growth kinetics[16].\u003c/p\u003e \u003cp\u003eHowever, these holes or facets can introduce many significant factors impacting oxidation, such as orientations, steps, and edges[26,28,29]. How these holes/facets change oxidation outcomes, and how well oxidation on the facets replicates oxidation of the bulk, is unclear. In this work, we performed \u003cem\u003ein situ\u003c/em\u003e ETEM oxidation experiments on Cu thin films with faceted holes exposing Cu(100) and (110) facets at different temperatures, to directly compare oxidation dynamics on different facet orientations with flat surfaces.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cp\u003eSingle-crystalline Cu(100) thin film samples with a thickness of 60 nm were grown on a NaCl(100) substrate using an ultra-high-vacuum (UHV) \u003cem\u003ee\u003c/em\u003e-beam evaporator at 300 ˚C[16]. The films were transferred to TEM Cu mesh grids using the float-off method[16] by dissolving the NaCl substrate in ultra-pure water. The sample was cleaned by float-off in fresh ultra-pure water for several times to remove residual NaCl.\u003c/p\u003e \u003cp\u003e \u003cem\u003eIn situ\u003c/em\u003e ETEM experiments were carried out on these thin film samples using a dedicated differentially pumped environmental TEM (Hitachi H-9500 ETEM) operating at 300 keV with a home-built gas delivery system with gas up to 0.1 Pa. A double-tilt furnace-type heating holder (Hitachi) was used to apply and control the temperature up to 800 ˚C. The sample temperature was calibrated with fixed melting-point samples to ensure accurate temperature measurement. To avoid contamination impacting the oxidation result, the ETEM chamber was baked out before each oxidation experiment, the holder was plasma cleaned before each experiment, and the samples were freshly grown before each ETEM experiment.\u003c/p\u003e \u003cp\u003eAs-grown Cu thin films are continuous single crystalline films, with small holes resulting from film thickness (~\u0026thinsp;60 nm). Due to unavoidable air exposure during transferring as-grown samples from the evaporator chamber to the TEM (~\u0026thinsp;30 min), as-grown thin films are slightly oxidized, forming small few-nanometer sized nano-oxide islands. \u003cem\u003eIn situ\u003c/em\u003e ETEM experiments start with annealing these thin films in 0.1 Pa H\u003csub\u003e2\u003c/sub\u003e under ~\u0026thinsp;600 ˚C to reduce native oxides on the film. This hydrogen annealing process also creates larger (~\u0026thinsp;hundred nm) faceted holes exposing Cu(100) and (110) facets on the thin film, as well as remove defects such as dislocations on the sample, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Since holes expand quickly at higher temperatures and can cause films to break, 600 ˚C was chosen as the maximum temperature for oxidation of Cu films with holes. \u003cem\u003eIn situ\u003c/em\u003e oxidation experiments were then performed under O\u003csub\u003e2\u003c/sub\u003e, varying temperature (200\u0026ndash;600 ˚C) and pressure.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eOxidation at low temperature (200–350 ˚C)\u003c/h2\u003e \u003cp\u003eUnder low temperatures (200–350 ˚C), small (\u0026lt; 10 nm) oxide islands were observed to form on the faceted holes. The oxide islands are similar to native oxides on Cu films formed at room temperature. Using \u003cem\u003ein situ\u003c/em\u003e ETEM, the nucleation sequence of nano-islands on different facets is characterized. Due to the low temperature, the oxidation speed is much lower at the same oxidizing pressure. For example, at 250 ˚C under 0.03 Pa O\u003csub\u003e2\u003c/sub\u003e, it took two hours of oxygen exposure until oxide nano-islands were observed. To accelerate the oxidation process, higher oxygen pressure (0.1 Pa) was used at low temperatures. This reduced the amount of time needed to form observable oxides to tens of minutes.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, oxide islands were first observed on Cu(110) facets at 250˚C under 0.1 Pa O\u003csub\u003e2\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea-b), then they were seen on Cu(100) facets (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). The time sequence over which each oxide island formed is plotted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, which shows a clear trend of oxide nucleation preference on Cu(110) facets over Cu(100) facets. During this process depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee-f, oxide nano-islands are mainly observed along the hole, rather than on the flat surface. They mostly demonstrate outward oxidation behavior, that is, oxide growth on oxide surfaces without significantly changing the underlying metal surfaces. These results indicate diffusing Cu atoms near the holes are the major Cu source for oxides during this stage. This is consistent with our previous HRTEM observation of oxide growth at a similar condition (300 ˚C, 0.03 Pa O\u003csub\u003e2\u003c/sub\u003e)[16], which shows layer-by-layer oxide growth on the Cu\u003csub\u003e2\u003c/sub\u003eO surface. Such growth occurs without consumption of the metal substrate under the oxide island, until surface diffusing Cu atoms are depleted.\u003c/p\u003e \u003cp\u003eDuring the early oxidation, oxide nano-islands were only observed near the holes (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee-f). After a longer oxidation time (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eg), oxide nano-islands were observed on Cu(001) thin film surfaces. Selected area electron diffraction (SAED) patterns (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eh) show Cu\u003csub\u003e2\u003c/sub\u003eO nano-islands follow cube-on-cube epitaxy with Cu(001) substrates. Oxide islands on Cu surfaces demonstrate homogenous, uniform distributions along surfaces, similar to previous experimental observations on flat Cu surfaces [17,18,21]. Over this temperature range, an oxidation preference sequence of Cu(110) facet \u0026gt; Cu(100) facet \u0026gt; \u0026gt; Cu(001) flat surface is resolved. Thus, holes can significantly accelerate oxidation by introducing edges, preferable facet orientations, and free Cu atoms diffusing on surfaces.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eOxidation at medium temperature (350–450 ˚C)\u003c/h2\u003e \u003cp\u003eUnder a medium temperature range (350–450 ˚C), larger oxides (~ 100 nm in at least one dimension) are observed to form along Cu(110) facets (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, needle-shaped oxides were observed to nucleate on Cu(110) facets at 350 ˚C. As depicted by the oxide on the rightward (110) facet, nucleating Cu\u003csub\u003e2\u003c/sub\u003eO initially occurs only on {100} facets, growing in both width and height while maintaining its triangular shape. When the height of the oxide reached ~ 15 nm, a {110} interface formed at its bottom. This resulted in a trapezoid-shaped oxide with {100} side facets and {110} bottom facets (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). Then, this oxide grew mainly along its width, while its height remained almost constant. Both high-resolution (HRTEM) image (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) and the SAED pattern (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec) suggest Cu\u003csub\u003e2\u003c/sub\u003eO islands formed under this condition also share cube-on-cube epitaxy with the Cu substrate.\u003c/p\u003e \u003cp\u003eIn contrast, few oxides were observed to nucleate on Cu(100) facets. Oxides nucleating on Cu(100) facets are observed only on larger holes (Cu(100) facet \u0026gt; 100 nm), not on smaller holes. This is probably due to the fact that on smaller holes the distances between oxides -- from oxides that first nucleate on Cu(110) and oxides that will subsequently nucleate on the Cu(100) facets -- are insufficient for the average oxide distance under this condition. Only larger holes with large Cu(100) facets can provide enough space for the widely spaced nucleating oxides. On the Cu(001) flat surface, right-triangle-shaped Cu\u003csub\u003e2\u003c/sub\u003eO are observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). They feature {100} short edges and {110} long edges, respectively marked by dashed red and blue lines. These triangular-shaped oxide islands are consistent with previous literature reports on uniform Cu thin films.[17,30]\u003c/p\u003e \u003cp\u003eAt 450˚C, oxides are also observed to nucleate on Cu(110) facets first (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee), forming rectangular-shaped oxides with {110} facets. On flat Cu(001) surfaces, right-triangular-shaped Cu\u003csub\u003e2\u003c/sub\u003eO islands are also observed, exposing {100} short edges and {110} long edges (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef). Compared with outcomes at 350 ˚C, oxide densities decrease and average oxide distances increase, while larger oxide islands were observed after the same oxidation time.\u003c/p\u003e \u003cp\u003eUnder this temperature range, oxide formation follows the sequence of Cu{110} facet \u0026gt; Cu{100} facet \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e≥\u003c/span\u003e Cu(001) surface. Oxides grown on facets show both inward and outward oxidation, that is, oxides grow both on the metal-oxide interface and on the oxide surface. These results indicate that under these conditions, Cu atoms from facets are the main Cu source for Cu\u003csub\u003e2\u003c/sub\u003eO growth on holes. During the oxidation process, O from faceted holes serves as the main O source for Cu\u003csub\u003e2\u003c/sub\u003eO, such that O needs to diffuse through the oxide to form new Cu\u003csub\u003e2\u003c/sub\u003eO. This leads to self-limiting oxidation in the depth direction \u0026lt; 110\u0026gt;, which forms observed needle-shaped islands on Cu(110) facets.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eOxidation at high temperatures (500–600˚C)\u003c/h2\u003e \u003cp\u003eUnder high temperatures (500–600 ˚C), oxide islands form much faster and grow into larger and more faceted shapes. Unlike lower temperatures that prefer nucleation at Cu(110) facets, oxides at high temperatures prefer to nucleate at Cu(100) facets (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAt 500 ˚C, a mixture of oxides nucleating on both Cu(100) and Cu(110) facets are observed, indicating that their nucleation preferences are similar (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). Oxides nucleating on Cu(110) facets feature {100} (red) and {110} (blue) interfaces, similar to those formed in the medium-temperature range. However, the oxides grown on Cu(100) facets show a directional growth into Cu substrates along the \u0026lt; 110 \u0026gt; direction, forming rods. The sides of the rods are oriented along {024} facets (green).\u003c/p\u003e \u003cp\u003eAt 550 ˚C and 600 ˚C, oxides are only observed to nucleate on Cu(100) facets (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb-e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec). These oxides feature higher index facets like {024} (green), and lower index facets such as {100} (red) and {110} (blue). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec-e, the metal-oxide interfaces along the \u0026lt; 100 \u0026gt; and \u0026lt; 110 \u0026gt; directions grow much faster than along the \u0026lt; 024 \u0026gt; directions. This is evidenced by the size evolution of the oxide, and the consumption of Cu near the Cu\u003csub\u003e2\u003c/sub\u003eO||Cu{100} interface, as the originally faceted hole (dashed line) became concave.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef, oxide nucleation on Cu(100) facets requires a relatively large Cu(100) facet. When the Cu(100) facet is too small, Cu\u003csub\u003e2\u003c/sub\u003eO is observed to form only on Cu(001) surfaces, forming square-shaped islands exposing {110} facets. This oxide shape on flat surfaces is consistent with previous literature reports at this temperature.[17] Oxides forming on flat surfaces show random distributions, regardless of their relative distances from holes. This result indicates oxide nucleation on Cu(001) surfaces is preferred over that on Cu(110) facets at high temperatures.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAfter prolonged oxidation, all holes with Cu(100) facets are oxidized, forming zig-zag shaped oxide rods bending at holes (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea-c). The rods show side facets along {013} (yellow), {024} (green), or {015} (purple) orientations, and a top facet along {010} (red). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the oxide grows mainly in the length direction (along \u0026lt; 010\u0026gt;), while the width of the rods maintains almost unchanged. This is similar to the observation in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb-d, indicating the Cu\u003csub\u003e2\u003c/sub\u003eO||Cu \u0026lt; 010 \u0026gt; direction is the preferred oxide growth direction. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed plots each actual oxide rod length between {020} rod tip and the nearest hole facet, while Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee measures the relative length changes from Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a). Both lengths are measured along the \u0026lt; 010 \u0026gt; direction perpendicular to the rod tip surface ({020}, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee confirms the growth rates of each rod are similar (3.8 ± 0.5 nm/min), following a quasi-linear relationship with time regardless of the initial length (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed), width, or side facet orientation of each rod. This result indicates that the O source for Cu\u003csub\u003e2\u003c/sub\u003eO rod growth is coming from absorbed O on Cu film surfaces, instead of O on holes that needs to diffuse through the oxide. Because if the latter case was true, growth rate would decrease with increasing oxide thickness.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHence, in this high-temperature range (500–600 ˚C), the oxidation preference sequence follows Cu(100) facet \u0026gt; Cu(001) surface \u0026gt; \u0026gt; Cu(110) facet. The oxidation of Cu(100) faceted holes demonstrates inward oxidation, that is, oxide growth into metal, without expanding on the original metal surface. O on the Cu surface serves as the O source for Cu\u003csub\u003e2\u003c/sub\u003eO growth rather than O from the faceted hole, which was observed at medium and low temperatures.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Summary and Outlooks","content":"\u003cp\u003eIn summary, we systematically investigated the oxidation of Cu(100) thin films with faceted holes along Cu{100} and Cu{110} under 0.03 Pa O\u003csub\u003e2\u003c/sub\u003e between temperatures 200 and 650°C at a temperature interval of 50°C. The oxide morphology and formation sequence changed with increasing temperature as summarized below and in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e:\u003c/p\u003e\u003cul\u003e \u003cli\u003e \u003cp\u003eAt low temperature (200–300°C, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea,d), high densities of \u0026lt; 5 nm Cu\u003csub\u003e2\u003c/sub\u003eO nano-islands were observed. The sequence of the oxide formation was Cu(110) facet \u0026gt; Cu(100) facet \u0026gt; Cu(001) surface. Outward oxidation is noted, indicating that diffusing Cu near faceted holes is the source of Cu during oxide formation.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAt medium temperature (350–450°C, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb,e), needle-shaped Cu\u003csub\u003e2\u003c/sub\u003eO islands were observed on Cu(110) facets. Right-triangular-shaped Cu\u003csub\u003e2\u003c/sub\u003eO islands were observed on flat surfaces with short edges along Cu{100}, and long edges along Cu{110} directions. Oxidation preference follows the order of Cu(110) facet \u0026gt; Cu(100) facet ≥ Cu(001) surface. Oxidation is observed to grow both inward and outward on Cu(110) facets, and oxide growth shows self-limiting growth perpendicular to the Cu(110) facet. These observations indicate that Cu and O from these facets are the sources of Cu and O during oxide formation.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAt high temperature (500–600°C, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec,f), the oxidation preference changed to Cu(100) facet \u0026gt; Cu(001) surface \u0026gt; \u0026gt; Cu(110) facet. Faceted rod-like oxides were observed on Cu(100) facets, with side surfaces of ~{240} planes, and top surfaces of {100} planes. Rod-like oxides mainly grow inward at Cu\u003csub\u003e2\u003c/sub\u003eO|Cu(100) interfaces, with quasi-linear growth rates regardless of distance from their nearest hole facets. This indicates oxygen from Cu(001) surfaces is the O source for oxide growth on Cu(100) facets.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e\u003cp\u003eOur results directly compare the oxidation preference and dynamics of different orientations under identical conditions (temperature, pressure, oxidation time, purity, \u003cem\u003eetc\u003c/em\u003e). It was previously believed that Cu(110) oxidation is preferred over that on Cu(100) due to easier O diffusion on reconstructed Cu(110) surfaces.[19] However, we observe the change of preferred oxidation orientation from Cu(110) to Cu(100) over a critical temperature of 500°C. The mechanism for this switch at higher temperature might be a change in lattice mismatch (strain) over temperature, or associated surface stresses. Previous research on CuAu alloy oxidation showed faster oxide nucleation and growth rates with increased Au composition due to reduced interfacial strain[17,26,31], indicating the oxide nucleation and growth rate can be tuned by interfacial strain. At different oxidation temperature as shown in this paper, due to the different thermal expansion of different Cu and Cu\u003csub\u003e2\u003c/sub\u003eO orientations, the interfacial strain changes, which might lead to the observed switch in oxidation facet preference. Alternatively, changes in relative ordering of O adsorption over different facets, or surface structure changes from processes such as reconstruction, may also induce this switch. Given prior work on defects such as surface steps and edges[16,25,29,32,33], changes in surface structures impacting oxidative preferences can also affect corresponding switching. In-depth mechanistic explanation of this phenomenon requires further theoretical simulations and higher resolution experimental investigations, which require \u003cem\u003ein situ\u003c/em\u003e experiments at higher time resolution and more stable heating stages under higher temperatures.\u003c/p\u003e\u003cp\u003eMoreover, our results also highlight that inward oxidation (growth at metal-oxide interface) or outward oxidation (growth at oxide surface) behavior, which was considered to be constant for a given material, can be changed by adjusting temperature and/or Cu and O sources. These findings unveil a promising avenue for manipulating oxide structure. This also provides a caveat for future \u003cem\u003ein situ\u003c/em\u003e TEM studies on oxidation: as sample thickness reduces, metal or oxygen sources can differ from those of bulk. This may vary oxidation outcomes versus those of bulk, especially when oxide size is comparable to that of sample thickness.\u003c/p\u003e\u003cp\u003eThese experiments systematically compare oxidation behaviors by solely changing temperature, while keeping other reaction conditions constant. Such controlled experiments show differences in oxide morphologies, oxide growth mechanism, and orientation preferences. These differences reveal complexity in the metal oxidation process. By changing temperature, many important oxidation steps – such as oxygen chemisorption, oxygen and/or metal diffusion, and oxide growth mechanisms – can change. Hence, more systematic and concerted experimental and theoretical investigations are needed to gain a more comprehensive understanding of early-stage oxidation, which will guide the advanced fabrication and engineering of nano-oxides.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.C.Y. and W.A.S. conceived and directed the project. M.L. conducted the experiments, data analysis, and drafted the manuscript. M.T.C. conducted D.F.T. simulations. S.H. contributed to data analysis. All authors contributed to results discussion and manuscript refinement.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors acknowledge the funding support from NSF grants DMR-1410055, DMR-1508417, DMR-1410335, CBET-2130804 and CMMI-1905647, as well as support from Hitachi High Technologies and technical assistance from the Nanoscale Fabrication and Characterization Facility (NFCF) in the Petersen Institute of Nano Science and Engineering (PINSE) at the University of Pittsburgh. This research used Electron Microscopy resources of the Center for Functional Nanomaterials (CFN), which is a U.S. Department of Energy Office of Science User Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology \u0026amp; Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE\u0026rsquo;s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData is provided within the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGattinoni C, Michaelides A. Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides. \u003cem\u003eSurface Science Reports\u003c/em\u003e. 2015;70:424-447.\u003c/li\u003e\n\u003cli\u003eJensen F, Besenbacher F, Laegsgaard E, Stensgaard II. 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Enhanced Mass Transfer in the Step Edge Induced Oxidation on Cu(100) Surface. \u003cem\u003eJournal of Physical Chemistry C\u003c/em\u003e. 2017;121:11251-11260.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"high-temperature-corrosion-of-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [High Temperature Corrosion of Materials](https://www.springer.com/journal/11085)","snPcode":"11085","submissionUrl":"https://submission.nature.com/new-submission/11085/3","title":"High Temperature Corrosion of Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"in situ, environmental TEM, oxidation, facets, holes","lastPublishedDoi":"10.21203/rs.3.rs-4743879/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4743879/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFundamental understanding of surface oxidation dynamics is critical for rational corrosion protection and advanced manufacturing of nanostructured oxides. \u003cem\u003eIn situ\u003c/em\u003e Environmental TEM (ETEM) provides high spatial (nano- to atomic- scale) and temporal (\u0026lt;\u0026thinsp;0.1 second) resolution to investigate the early-stage oxidation/corrosion dynamics of metals and alloys. Thin samples with facets are widely used to enable cross-sectional observation of the oxidation dynamics in ETEM. However, how different facet orientations oxidize under the same conditions, and how these facets change the oxidation process, has not been investigated before. Using \u003cem\u003ein situ\u003c/em\u003e ETEM, we systematically compare the oxidation dynamics of Cu(001) thin films, with faceted holes exposing {100} and {110} facets at temperatures ranging from 250\u0026ndash;600 ˚C under 0.03 Pa O\u003csub\u003e2\u003c/sub\u003e. Oxidation preference is observed to change, from Cu(110) facets at lower temperatures to Cu(100) facets at ~\u0026thinsp;500 ˚C. Oxide growth mechanisms change from outward growth on Cu\u003csub\u003e2\u003c/sub\u003eO surfaces at low temperatures, to inward growth on Cu-Cu\u003csub\u003e2\u003c/sub\u003eO interfaces at high temperatures. At high temperatures (500\u0026ndash;600 ˚C), a rod-like Cu\u003csub\u003e2\u003c/sub\u003eO morphology is observed, with side facets of ~{024} and top facets of {100} on Cu(100). This differs from the square-shaped Cu\u003csub\u003e2\u003c/sub\u003eO exposing {110} facets formed on Cu(001) surfaces. Rod-like oxides exhibit directional growth along their lengths with linear growth rates, regardless of rod length and width. This suggests that O from Cu(001) surfaces, rather than Cu(100) facets, serves as an O source for oxide growth. These results show a direct comparison of oxidation at different orientations with temperature, underscoring the temperature dependence of oxidation preference. Our results also suggest future \u003cem\u003ein situ\u003c/em\u003e ETEM experiments viewing oxidation corrosion cross-sectionally should be cautious when oxide size is comparable with sample thickness, as the oxidizing mechanism may change due to sample thickness.\u003c/p\u003e","manuscriptTitle":"Temperature dependent early-stage oxidation dynamics of Cu(100) film with faceted holes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-09 08:54:55","doi":"10.21203/rs.3.rs-4743879/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Accepted","date":"2024-07-20T21:06:52+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-18T07:53:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"22023397579724329343500945674751299733","date":"2024-07-18T07:51:41+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-17T01:01:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-17T01:00:09+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-16T15:08:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"High Temperature Corrosion of Materials","date":"2024-07-15T15:20:49+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"high-temperature-corrosion-of-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [High Temperature Corrosion of Materials](https://www.springer.com/journal/11085)","snPcode":"11085","submissionUrl":"https://submission.nature.com/new-submission/11085/3","title":"High Temperature Corrosion of Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"76721978-3d82-4af0-ac17-fd57be5f7f6b","owner":[],"postedDate":"August 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-08-09T08:54:55+00:00","versionOfRecord":{"articleIdentity":"rs-4743879","link":"https://doi.org/10.1007/s11085-024-10274-7","journal":{"identity":"high-temperature-corrosion-of-materials","isVorOnly":false,"title":"High Temperature Corrosion of Materials"},"publishedOn":"2024-08-01 15:57:53","publishedOnDateReadable":"August 1st, 2024"},"versionCreatedAt":"2024-08-09 08:54:55","video":"","vorDoi":"10.1007/s11085-024-10274-7","vorDoiUrl":"https://doi.org/10.1007/s11085-024-10274-7","workflowStages":[]},"version":"v1","identity":"rs-4743879","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4743879","identity":"rs-4743879","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}