Metallic alloys

Friedel, J.

doi:10.1007/bf02751483

Cited by 1,746 publications

(524 citation statements)

References 17 publications

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“…slip plane (e.g., Friedel oscillations [32]) and to reduce computational cost, supercells periodic in all directions are used. Two types of supercells are necessary: one for the intrinsic I 1 and extrinsic E faults on the Basal plane, which can not be formed through a single shear operation; the other for the basal I 2 and SFs on the Prism and Pyramidal planes, which can be formed through a single shear operation.…”

Section: Dft Methodology and Simulation Geometriesmentioning

confidence: 99%

Comprehensive first-principles study of stable stacking faults in hcp metals

2017

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The plastic deformation in hcp metals is complex, with the associated dislocation core structures and properties not well understood on many slip planes in most hcp metals. A first step in establishing the dislocation properties is to examine the stable stacking fault energy and its structure on relevant slip planes. However, this has been perplexing in the hcp structure due to additional in-plane displacements on both side of the slip plane. Here, density functional theory guided by crystal symmetry analysis is used to study all relevant stable stacking faults in 6 hcp metals (Mg, Ti, Zr, Re, Zn, Cd). Specially, the stable stacking fault energy, position, and structure on the Basal, Prism I and II, Pyramidal I and II planes are determined using all-periodic supercells with full atomic relaxation. All metals show similar stacking fault position and structure as dictated by crystal symmetry, but the associated stacking fault energy, being governed by the atomic bonding, differs significantly among them. Stacking faults on all the slip planes except the Basal plane show substantial out-of-plane displacements while stacking faults on the Prism II, Pyramidal I and II planes show additional in-plane displacements, all extending to multiple atom layers. The in-plane displacements are not captured in the standard computational approach for stacking faults, and significant differences are shown in the energies of such stacking faults between the standard approach and fully-relaxed case. The existence of well-defined stable stacking fault on the Pyramidal planes suggests zonal dislocations are unlikely. Calculations on the equilibrium partial separation further suggests c + a dissociation into three * Corresponding author Email address: zhaoxuan.wu@epfl.ch (Zhaoxuan Wu) Preprint submitted to Acta Materialia October 9, 2016This is a pre-print of the following article: Yin, Binglun; Wu, Zhaoxuan; Curtin, W.A. Acta Materialia 2017, 123, 223--234.. The formal publication is available at http://dx.doi.org/10.1016/j.actamat.2016.10.042 partials on the Pyramidal I plane is unlikely and c dissociation on Prism planes is unlikely to be stable against climb-dissociation onto the Basal planes in these metals.

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Section: Dft Methodology and Simulation Geometriesmentioning

confidence: 99%

Comprehensive first-principles study of stable stacking faults in hcp metals

2017

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“…The invention of the scanning tunnelling microscope 2 (STM) allowed the visualization of this effect in the real space by looking at the spectacular standing wave patterns produced by elastic scattering of electrons and holes at surface defects, such as vacancies, adsorbates, impurities or step edges [3][4][5][6] . These waves, known as Friedel oscillations 7 , correspond to modulations of the electronic local density of states 8 (LDOS) and can be energetically resolved by differential conductivity (dI/dU) maps, usually measured at low temperature to reach a large coherence length and an improved energy resolution.…”

mentioning

confidence: 99%

“…Recently, it has been further expanded to study spin-split surface states on surface alloys 10 and topological insulators 11,12 . QPI has proven to be a powerful method to analyse electronic properties, such as energy dispersion relations 13 , lifetimes [14][15][16] , scattering phase shifts 1,7 , coherence lengths 9 and scattering channels 10,11,12 . One of the fundamental aspects of the QPI mapping is that in real space the amplitude of the LDOS oscillations reduces as the tip is moved away from the scattering centres.…”

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confidence: 99%

Direct observation of many-body charge density oscillations in a two-dimensional electron gas

et al. 2015

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Quantum interference is a striking manifestation of one of the basic concepts of quantum mechanics: the particle-wave duality. A spectacular visualization of this effect is the standing wave pattern produced by elastic scattering of surface electrons around defects, which corresponds to a modulation of the electronic local density of states and can be imaged using a scanning tunnelling microscope. To date, quantum-interference measurements were mainly interpreted in terms of interfering electrons or holes of the underlying band-structure description. Here, by imaging energy-dependent standing-wave patterns at noble metal surfaces, we reveal, in addition to the conventional surface-state band, the existence of an 'anomalous' energy band with a well-defined dispersion. Its origin is explained by the presence of a satellite in the structure of the many-body spectral function, which is related to the acoustic surface plasmon. Visualizing the corresponding charge oscillations provides thus direct access to many-body interactions at the atomic scale.

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“…57 The discrepancy between SC-ISJM and first-principles electron densities near r = 0 originates from the r 2 weight factor which is used in spherical average.…”

Section: B Sc-isjm Resultsmentioning

confidence: 99%

Density-functional theory study of ionic inhomogeneity in metal clusters using SC-ISJM

Payami

Mahmoodi

2017

Surface Science

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In this work we have applied the recently formulated self-compressed inhomogeneous stabilized jellium model [M. Payami and T. Mahmoodi, Can. J. Phys. 89, 967 (2011)] to describe the equilibrium electronic and geometric properties of atomic-closed-shell simple metal clusters of AlN (N =13, 19, 43, 55, 79, 87, 135, 141), NaN , and CsN (N =9,15,27,51, 59, 65, 89, 113). To validate the results, we have also performed first-principles pseudo-potential calculations and used them as our reference. In the model, we have considered two regions consisting of "surface" and "inner" ones, the border separating them is sharp. This generalization makes possible to decouple the relaxations of different parts of the system. The results show that the present model correctly predicts the size reductions seen in most of the clusters. It also predicts increase in size of some clusters, as observed from first-principles results. The other property is the change of inter-layer distances, which in most cases were realized as contractions and in a few cases as expansions, are reproduced in good agreement with the atomic simulation results. For a better description of the properties, it is possible to improve the method of choosing the thicknesses or generalize the model to include more regions than just two.

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Metallic alloys

Cited by 1,746 publications

References 17 publications

Comprehensive first-principles study of stable stacking faults in hcp metals

Comprehensive first-principles study of stable stacking faults in hcp metals

Direct observation of many-body charge density oscillations in a two-dimensional electron gas

Density-functional theory study of ionic inhomogeneity in metal clusters using SC-ISJM

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