Atomistic simulations of amorphous alumina surfaces

Adiga, Shashishekar P.; Zapol, Peter; Curtiss, Larry A.

doi:10.1103/physrevb.74.064204

Cited by 90 publications

(110 citation statements)

References 30 publications

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“…3(a), Al-O, O-O, and Al-Al peaks can be seen at around 0.18, 0.28, and 0.32 nm, respectively, which is in good agreement with a number of experimental and simulated PDFs of amorphous and liquid Al 2 O 3 . 5,6,[15][16][17][18][19] The PDFs for as-deposited and annealed EB-Al 2 O 3 at 973 and 1073 K are almost consistent with respect to peak intensity and position.…”

Section: Simulation Proceduresmentioning

confidence: 66%

Enhancement of nanovoid formation in annealed amorphous Al2O3 including W

Nakamura

Ishimaru

Hirata

et al. 2011

Journal of Applied Physics

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The effect of W on the nanovoid formation in annealed amorphous Al 2 O 3 was studied by transmission electron microscopy and molecular dynamics simulations. A comparison of the void formation behavior in electron-beam deposited Al 2 O 3 (without W) and resistance-heating deposited Al 2 O 3 (with 10 at. % W) revealed that W enhances the formation and growth of nanovoids. An analysis of the pair distribution function (PDF) in both types of amorphous Al 2 O 3 showed that the introduction of W into amorphous Al 2 O 3 brings about a significant change in the amorphous structure. Furthermore, it was found by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) that sub-nm sized W clusters exist in as-deposited Al 2 O 3 prepared by resistance-heating and then dissolve in the amorphous matrix with annealing. The combination of PDF analysis and HAADF-STEM observation provides evidence that the enhancement of void formation originates in the heterogeneous short-range atomic configurations induced by the addition of W.

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Section: Simulation Proceduresmentioning

confidence: 66%

Enhancement of nanovoid formation in annealed amorphous Al2O3 including W

Nakamura

Ishimaru

Hirata

et al. 2011

Journal of Applied Physics

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“…Atomic rearrangements in the alumina layer are responsible for its densification, since γ-Al 2 O 3 has a higher density than amorphous alumina ( Table 2). The difference ranges from about 10 up to 40% because the density of the amorphous phase of alumina varies over an exceptionally large range, between 2.1 and 3.5 g/cm 3 [10][11][12], which suggests the existence of amorphous polymorphism [12,13]. Anyway, for the alumina film covering aluminium powder particles, the specific volume ratio γ-Al 2 O 3 / Al of ~1.2 is generally assumed [15].…”

Section: Transformation Of Amorphous Alumina Into Crystalline γ -Al 2mentioning

confidence: 99%

Disruption of an Alumina Layer During Sintering of Aluminium in Nitrogen

Pieczonka¹

2017

Archives of Metallurgy and Materials

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Aluminium oxide layer on aluminium particles cannot be avoided. However, to make the metal-metal contacts possible, this sintering barrier has to be overcome in some way, necessarily to form sintering necks and their development. It is postulated that the disruption of alumina layer under sintering conditions may originate physically and chemically. Additionally, to sinter successfully non alloyed aluminium powder in nitrogen, the operation of both types mechanism is required. It is to be noted that metallic aluminium surface has to be available to initiate reactions between aluminium and the sintering atmosphere, i.e. mechanical disruption of alumina film precedes the chemical reactions, and only then chemically induced mechanisms may develop. Dilatometry, gravimetric and differential thermal analyses, and microstructure investigations were used to study the sintering response of aluminium at 620°C in nitrogen, which is the only sintering atmosphere producing shrinkage.

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“…The definition of thickness of the surface in [13] is somewhat arbitrary: all atoms that were within 5 Å of the hull just touched the exterior of the droplet, and were considered to belong to the surface, atoms that had the distance between 5 Å and 8 Å from the hull belong to the transition zone and the remaining atoms belong to the interior. In contrast, no definition of surface was clearly presented for the amorphous Al 2 O 3 thin film; they used the top 1 Å or 3 Å layer of the amorphous thin film for surface structural studies [24]. From structural point of view, it can be considered that atoms belong to the surface if they could not have full coordination for all atomic pairs in principle and in contrast, atoms belong to the core if they could have full coordination for all atomic pairs in principle like those located in the bulk.…”

Section: Calculationmentioning

confidence: 99%

Evolution of structure of SiO2nanoparticles upon cooling from the melt

Huynh

Hoang

Zung³

2008

PMC Phys B

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Evolution of structure of spherical SiO 2 nanoparticles upon cooling from the melt has been investigated via molecular-dynamics (MD) simulations under non-periodic boundary conditions (NPBC). We use the pair interatomic potentials which have weak Coulomb interaction and Morse type short-range interaction. The change in structure of SiO 2 nanoparticles upon cooling process has been studied through the partial radial distribution functions (PRDFs), coordination number and bond-angle distributions at different temperatures. The core and surface structures of nanoparticles have been studied in details. Our results show significant temperature dependence of structure of nanoparticles. Moreover, temperature dependence of concentration of structural defects in nanoparticles upon cooling from the melt toward glassy state has been found and discussed.

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Atomistic simulations of amorphous alumina surfaces

Cited by 90 publications

References 30 publications

Enhancement of nanovoid formation in annealed amorphous Al2O3 including W

Enhancement of nanovoid formation in annealed amorphous Al2O3 including W

Disruption of an Alumina Layer During Sintering of Aluminium in Nitrogen

Evolution of structure of SiO2nanoparticles upon cooling from the melt

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