Are clusters physical entities?

Rösch, Frohmut; Trebin, Hans‐Rainer

doi:10.1524/zkri.2008.1056

Cited by 3 publications

(4 citation statements)

References 13 publications

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“…The terrace structure of QCs that were cut slightly tilted with respect to a facet (flat atomic layer) reflects the distances between quasilattice planes. It also shows that the clusters in IQCs are not stable subunits that maintain their shapes at the surface, as suggested a while ago (Rö sch & Trebin, 2008). In contrast, the flat surface runs through the clusters along flat atomic layers , and references therein).…”

Section: Surface Structure Analysismentioning

confidence: 58%

Quasicrystals: What do we know? What do we want to know? What can we know?

Steurer

2018

Acta Crystallogr A Found Adv

101

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More than 35 years and 11 000 publications after the discovery of quasicrystals by Dan Shechtman, quite a bit is known about their occurrence, formation, stability, structures and physical properties. It has also been discovered that quasiperiodic self-assembly is not restricted to intermetallics, but can take place in systems on the meso-and macroscales. However, there are some blank areas, even in the centre of the big picture. For instance, it has still not been fully clarified whether quasicrystals are just entropy-stabilized high-temperature phases or whether they can be thermodynamically stable at 0 K as well. More studies are needed for developing a generally accepted model of quasicrystal growth. The state of the art of quasicrystal research is briefly reviewed and the main as-yet unanswered questions are addressed, as well as the experimental limitations to finding answers to them. The focus of this discussion is on quasicrystal structure analysis as well as on quasicrystal stability and growth mechanisms.

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Section: Surface Structure Analysismentioning

confidence: 58%

Quasicrystals: What do we know? What do we want to know? What can we know?

Steurer

2018

Acta Crystallogr A Found Adv

101

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“…There is still an ongoing discussion pro and contra the mechanical stability of the clusters. [12][13][14] This was the motivation for our first-principle calculations performed for a better understanding of the inter-and intracluster interactions with focus on the mechanical properties. This work focuses mainly on static equilibrium surfaces; no kinetic or nonequilibrium processes have been included.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties of clusters in quasicrystal approximants: The example of the 1/1 Al-Cu-Fe approximant

Jung¹,

Steurer²

2011

Phys. Rev. B

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Quantum-mechanical molecular dynamics have been used to investigate structural and physical properties of the 1/1 approximant of the icosahedral Al-Cu-Fe quasicrystal. Particular local structural arrangements of atoms, referred to here as clusters, have been analyzed with respect to their properties within the crystal structure. Artificial strain and cracks have been introduced to probe their mechanical properties, and artificial surfaces have been created to investigate their role for surface termination. From the energetics of the ab initio calculations results that flat surfaces cutting clusters are favored over puckered surfaces keeping clusters intact. The Vienna Ab-initio Simulation Package (VASP) was used for all calculations.

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“…Hence, in general, fracture surfaces are not explicitely those of lowest energy or lowest roughness. Furthermore, due to the dynamic process, the crack tip heatens up and acoustic waves are emitted from the crack line as atomic bonds break [5,20,21].…”

mentioning

confidence: 99%

“…Bending of the crack front is not restricted to the atomic level. In more complex systems like quasicrystals, containing clusters [5,20,21,[23][24][25] or inclusions, the crack front tends to avoid the obstacles and is deviating from a straight line on a larger scale.…”

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confidence: 99%

Crack front propagation by kink formation

Rösch¹,

Trebin²

2009

Europhys. Lett.

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Fracture of a three-dimensional brittle solid generates two-dimensional surfaces, which are formed behind a one-dimensional crack front. For quasi-static cracks on a (111) cleavage plane in silicon front propagation by kink-pair formation was proposed and proven by a reaction-pathway analysis with Stillinger-Weber potentials. Here, we demonstrate that the kink-pair mechanism is much more general: We also observe it in molecular dynamics simulations of a complex metallic alloy, the C15 NbCr2 Friauf-Laves phase, where we applied carefully selected embedded-atommethod potentials. The numerical experiments highlight that kink formation is essential for crack propagation in any brittle material.

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Are clusters physical entities?

Cited by 3 publications

References 13 publications

Quasicrystals: What do we know? What do we want to know? What can we know?

Quasicrystals: What do we know? What do we want to know? What can we know?

Mechanical properties of clusters in quasicrystal approximants: The example of the 1/1 Al-Cu-Fe approximant

Crack front propagation by kink formation

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