Effect of oxide grain structure on the high-temperature oxidation of Cr

Caplan, D.; Sproule, G. I.

doi:10.1007/bf00611694

Cited by 204 publications

(57 citation statements)

References 25 publications

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“…The dependence of oxidation rate on crystallographic orientation has also been suggested for Fe and Cr [9][10][11][12][13][14]. In oxidation studies on Ni single crystals, more rapid oxidation is consistently observed on (001) faces than on (111) faces [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 83%

“…As with Ni, the maximum relative oxide height decreased with increasing oxidation time; no resolvable differences in oxide height could be observed after 5 min. This phenomenon occurs more quickly in Cr than in Ni, indicating that the effect of substrate orientation on oxidation may be less important or that diffusion through oxide grain boundaries is more effective [14].…”

Section: Orientation Dependent Oxidation In Bcc Metalsmentioning

confidence: 99%

“…The different results found by these authors suggest that not only does the orientation affect the oxidation rate and possibly the mechanism as well, but so too does the temperature. For Cr, work by Caplan and Sproule [14] has shown that some orientations of Cr lead to the growth of a thin, monocrystalline oxide, whereas others developed a thicker, polycrystalline oxide. However, the orientations that lead to each behavior were not identified.…”

Section: Introductionmentioning

confidence: 99%

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Effects of crystallographic orientation on the early stages of oxidation in nickel and chromium

Bonfrisco

Frary

2009

J Mater Sci

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Surface orientation plays an important role in the oxidation behavior of single crystals where studies have found the relative oxidation rates for surfaces with different orientations. However, most materials are polycrystalline and contain myriad orientations that contribute to the overall oxidation process. Here we determine the effects of orientation on the early stages of oxidation behavior as a function of surface orientation for polycrystalline nickel (face-centered cubic) and chromium (body-centered cubic). After high temperature oxidation, the oxide topography is characterized using optical profilometry and the underlying microstructure is characterized with electron backscatter diffraction (EBSD). By correlating results from EBSD and optical profilometry, the oxide height is determined for each crystallographic orientation. In both Ni and Cr, a strong relationship is observed between the oxidation rate and direction of the surface normal; for Ni, (111) surfaces oxidize slowest, while (100) surfaces in Cr have the lowest oxidation rates. Although orientation-dependent oxidation rates are observed at short times, the effect is diminished at longer oxidation times.

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Section: Introductionmentioning

confidence: 83%

Section: Orientation Dependent Oxidation In Bcc Metalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of crystallographic orientation on the early stages of oxidation in nickel and chromium

Bonfrisco

Frary

2009

J Mater Sci

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“…Early oxidation studies of chromium had been performed from the 1950s to the beginning of the 1970s, and several studies on high temperature oxidation or nitridation behavior of chromium under a pure oxygen or nitrogen gas atmosphere had been reported. [12][13][14][15][16][17][18][19] Lillerud and Kofstad summarized the past oxidation kinetics studies of pure chromium, and discussed in detail the causes for the large variation in parabolic rate constant values reported in numerous past studies. 20,21) However, very few studies of oxidation and nitridation of chromium-based alloys in atmospheric heating have been carried out, 16,22) and no detailed analyses of scale and subsurface regions have yet been reported.…”

Section: Introductionmentioning

confidence: 99%

Oxidation or Nitridation Behavior of Pure Chromium and Chromium Alloys Containing 10 mass%Ni or Fe in Atmospheric Heating

et al. 2006

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“…Thermal oxide growth of Cr x O y primarily takes place through outward cation diffusion; thus new oxide forms mainly on top of the existing scale [21], increasing the resulting oxide layer overhang and gap size. Second, internal stresses generated within the (primarily) Cr layer due to inward diffusion of oxygen [22] may lead to elastic deformation of the underlying Cr. Shear stresses at the Cr/Cr x O y interface would produce a deformation of the Cr layer that would favor increased gap size and would increase with Cr layer thickness, as observed in the experiment (Fig.…”

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confidence: 99%

Nanogaps with very large aspect ratios for electrical measurements

Fursina

Lee

Sofin

et al. 2008

Applied Physics Letters

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For nanoscale electrical characterization and device fabrication it is often desirable to fabricate planar metal electrodes separated by large aspect ratio gaps with interelectrode distances well below 100 nm. We demonstrate a self-aligned process to accomplish this goal using a thin Cr film as a sacrificial etch layer. The resulting gaps can be as small as 10 nm and have aspect ratios exceeding 1000, with excellent interelectrode isolation. Such Ti/Au electrodes are demonstrated on Si substrates and are used to examine a voltage-driven transition in magnetite nanostructures. This shows the utility of this fabrication approach even with relatively reactive substrates.PACS numbers: 81.07. -b,81.16.-c,85.35.-p There is much interest in the electronic characterization of nanoscale materials and the creation of working molecular-based devices [1]. Both goals demand the fabrication of metallic electrodes separated by a distance comparable with the targeted length, i.e. a few nanometers. Much recent progress has been made in nanogap fabrication, and several techniques were proposed, including electromigration [2,3,4], electrodeposition [5,6], mechanically controlled break junctions [7], advanced ebeam lithography methods [8,9,10,11,12], on-wire lithography [13], etc. Interelectrode distances down to 1-2 nm may be achieved [4,6,9] by some of these methods, though without much control of gap aspect ratio.A significant challenge is fabricating two electrodes separated by a nanometer gap running parallel over a macroscopic width (high-aspect-ratio (HAR) nanogaps). HAR nanogap fabrication has been demonstrated based on a selective etching of cleaved GaAs/AlGaAs heterostructures [14,15]. However, this method requires particular substrates and allows only restricted gap geometries. A much simpler technique was proposed recently [16] with potentially no limitations on the width of the gap. Two separate lithographic patterning steps are used to define first and second electrodes, while the interelectrode separation is controlled by the oxidation of an Al sacrificial layer deposited upon the first electrode. The native aluminum oxide layer, Al 2 O 3 , overhangs the underlying metal and serves as a mask during the deposition of the second electrode. This layer must be removed afterwards, but since Al 2 O 3 , corundum, is one of the most chemically inert materials [17], removal by direct chemical etching is very difficult. In a refinement, the authors deposited an additional sacrificial layer of SiO 2 and subsequently used etchant for SiO 2 to remove the SiO 2 and Al/Al 2 O 3 layers [16]. The use of SiO 2 etchant greatly limits the use of this approach in conjunction with conventional silicon electronics. While this method potentially allows fabrication of HAR nanogaps, the reported aspect ratios are less than 10 [16].In this letter we report a highly reproducible and flexible method for nanometer-sized (10-20 nm) gap fabrication with aspect ratios exceeding 1000. Modifying the original method [16] by replacing the Al layer wi...

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Effect of oxide grain structure on the high-temperature oxidation of Cr

Cited by 204 publications

References 25 publications

Effects of crystallographic orientation on the early stages of oxidation in nickel and chromium

Effects of crystallographic orientation on the early stages of oxidation in nickel and chromium

Oxidation or Nitridation Behavior of Pure Chromium and Chromium Alloys Containing 10 mass%Ni or Fe in Atmospheric Heating

Nanogaps with very large aspect ratios for electrical measurements

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