Formation of a single quasicrystal upon collision of multiple grains

AbstractQuasicrystals exhibit long-range order but lack translational symmetry. When grown as single crystals, they possess distinctive and unusual properties owing to the absence of grain boundaries. Unfortunately, conventional methods such as bulk crystal growth or thin film deposition only allow us to synthesize either polycrystalline quasicrystals or quasicrystals that are at most a few centimeters in size. Here, we reveal through real-time and 3D imaging the formation of a single decagonal quasicrystal arising from a hard collision between multiple growing quasicrystals in an Al-Co-Ni liquid. Through corresponding molecular dynamics simulations, we examine the underlying kinetics of quasicrystal coalescence and investigate the effects of initial misorientation between the growing quasicrystalline grains on the formation of grain boundaries. At small misorientation, coalescence occurs following rigid rotation that is facilitated by phasons. Our joint experimental-computational discovery paves the way toward fabrication of single, large-scale quasicrystals for novel applications.

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Dislocation Nucleation and Propagation During Deposition of Cubic Metal Thin Films

MRS Proceedings ◽

10.1557/proc-677-aa7.32 ◽

2001 ◽

Vol 677 ◽

Author(s):

W. C. Liu ◽

Y. X. Wang ◽

C. H. Woo ◽

Hanchen Huang

Keyword(s):

Thin Films ◽

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Three Dimensional ◽

Thin Film Deposition ◽

Dislocation Nucleation ◽

Film Deposition ◽

Film Material ◽

Metal Thin Films ◽

Dynamics Simulations

ABSTRACTIn this paper we present three-dimensional molecular dynamics simulations of dislocation nucleation and propagation during thin film deposition. Aiming to identify mechanisms of dislocation nucleation in polycrystalline thin films, we choose the film material to be the same as the substrate – which is stressed. Tungsten and aluminum are taken as representatives of BCC and FCC metals, respectively, in the molecular dynamics simulations. Our studies show that both glissile and sessile dislocations are nucleated during the deposition, and surface steps are preferential nucleation sites of dislocations. Further, the results indicate that dislocations nucleated on slip systems with large Schmid factors more likely survive and propagate into the film. When a glissile dislocation is nucleated, it propagates much faster horizontally than vertically into the film. The mechanisms and criteria of dislocation nucleation are essential to the implementation of the atomistic simulator ADEPT.

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Heat Transport in Superlattices and Nanocomposites for Thermoelectric Applications

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.46.104 ◽

2006 ◽

Vol 46 ◽

pp. 104-110 ◽

Cited By ~ 2

Author(s):

Gang Chen

Keyword(s):

Thermal Conductivity ◽

Figure Of Merit ◽

Large Scale ◽

Energy Transport ◽

High Efficiency ◽

Waste Heat ◽

Thin Film Deposition ◽

Film Deposition ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure

Energy transport in nanostructures differs significantly from macrostructures because of classical and quantum size effects on energy carriers. Experimental results show that the thermal conductivity values of nanostructures such as superlattices are significantly lower than that of their bulk constituent materials. The reduction in thermal conductivity led to a large increase in the thermoelectric figure of merit in several superlattice systems. Materials with a large thermoelectric figure of merit can be used to develop efficient solid-state devices that convert waste heat into electricity. Superlattices grown by thin-film deposition techniques, however, are not suitable for large scale applications. Nanocomposites represent one approach that can lead to high thermoelectric figure merit. This paper reviews the current understanding of thermal conductivity reduction mechanisms in superlattices and presents theoretical studies on thermoelectric properties in semiconducting nanocomposites, aiming at developing high efficiency thermoelectric energy conversion materials.

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Molecular Dynamics Study of Cu Thin Film Deposition onβ-Ta

MRS Proceedings ◽

10.1557/proc-721-j2.3 ◽

2002 ◽

Vol 721 ◽

Cited By ~ 3

Author(s):

Peter Klaver ◽

Barend J. Thijsse

Keyword(s):

Molecular Dynamics ◽

Thin Film Deposition ◽

Film Deposition ◽

Boundary Structure ◽

Cu Films ◽

Grain Boundary Structure ◽

Cu Film ◽

Cu Thin Film ◽

Dynamics Simulations ◽

Atomically Flat

AbstractMolecular Dynamics simulations were performed to study Cu film deposition on β-Ta. Three different β-Ta surfaces were used, two being atomically flat, and one resulting from Ta on Ta growth. We find that the Cu films develop a (111) texture with vertical grain boundaries between grains having different epitaxial relations with the β-Ta substrate. The epitaxial rotation angles were determined, as 5.2° and 10-13°, and the resulting strain reductions in the Cu films were identified. The effects of the substrate differences on the interfacial Ta/Cu intermixing and the epitaxy and grain boundary structure of the films are discussed.

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Molecular Dynamics Simulations of Nanocrystalline Nickel and Copper Revealing Different Failure Model of FCC Metals

Materials Science Forum ◽

10.4028/www.scientific.net/msf.633-634.31 ◽

2009 ◽

Vol 633-634 ◽

pp. 31-38

Author(s):

Ajing Cao

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Grain Boundaries ◽

Large Scale ◽

Uniaxial Tensile ◽

Face Centered Cubic ◽

Triple Junctions ◽

Fcc Metals ◽

Face Centered ◽

Dynamics Simulations

We have previously reported that the fracture behavior of nanocrystalline (NC) Ni is via the nucleation and coalescence of nano-voids at grain boundaries and triple junctions, resulting in intergranular failure mode. Here we show in large-scale molecular dynamics simulations that partial-dislocation-mediated plasticity is dominant in NC Cu with grain size as small as ~ 10 nanometers. The simulated results show that NC Cu can accommodate large plastic strains without cracking or creating damage in the grain interior or grain boundaries, revealing their intrinsic ductile properties compared with NC Ni. These results point out different failure mechanisms of the two face-centered-cubic (FCC) metals subject to uniaxial tensile loading. The insight gained in the computational experiments could explain the good plasticity found in NC Cu not seen in Ni so far.

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A computational study of SrTiO3 thin film deposition: Morphology and growth modes

Journal of Materials Research ◽

10.1557/jmr.2009.0229 ◽

2009 ◽

Vol 24 (6) ◽

pp. 1994-2000 ◽

Cited By ~ 2

Author(s):

Jennifer L. Wohlwend ◽

Cosima N. Boswell ◽

Simon R. Phillpot ◽

Susan B. Sinnott

Keyword(s):

Thin Film ◽

Thin Films ◽

Computational Study ◽

Thin Film Deposition ◽

Layer Growth ◽

Film Deposition ◽

Layer By Layer ◽

Growth Modes ◽

Deposition Processes ◽

Dynamics Simulations

The growth of SrTiO3 (STO) thin films is examined using classical molecular dynamics simulations. First, a beam of alternating SrO and TiO2 molecules is deposited on the (001) surface of STO with incident kinetic energies of 0.1, 0.5, or 1.0 eV/atom. Second, deposition of alternating SrO and TiO2 monolayers, where both have incident energies of 1.0 eV/atom, is examined. The resulting thin film morphologies predicted by the simulations are compared to available experimental data. The simulations indicate the way in which the incident energy, surface termination, and beam composition influence the morphology of the thin films. On the whole, some layer-by-layer growth is predicted to occur on both SrO- and TiO2-terminated STO for both types of deposition processes, with the alternating monolayer approach yielding thin films with compositions that are much closer to that of bulk STO.

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Molecular dynamic simulations of plasticity and phase transition in Mg polycrystalline under shock compression

Applied Physics Express ◽

10.35848/1882-0786/ac43e3 ◽

2021 ◽

Author(s):

Zhiyong Jian ◽

Yangchun Chen ◽

Shifang xiao ◽

Liang Wang ◽

Xiaofan Li ◽

...

Keyword(s):

Phase Transition ◽

Grain Boundaries ◽

Large Scale ◽

Local Stress ◽

The Body ◽

Nonequilibrium Molecular Dynamics ◽

Dynamic Simulations ◽

Hexagonal Close Packed ◽

Dynamics Simulations ◽

Bcc Phase

Abstract We have investigated the shock-induced plasticity and phase transition in the hexagonal columnar nanocrystalline (HCN) Mg by large-scale nonequilibrium molecular dynamics simulations (NEMD). The preexisting grain boundaries (GBs) induce the nucleation of the {10-12} twins for the local stress relaxation. The twins grow up in grains leading to the orientation rotation. The phase transition from the hexagonal close-packed (HCP) phase to the body-centered cubic (BCC) phase begins when the migrating twin grain boundaries (TGBs) meet in A- and C-type grains, and continues in the plastic deformation regions. The phase-transition pathway involves two steps: the reorientation and phase transformation.

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Molecular-Dynamics Simulations of Laser-Ablation and Ionassisted Thin Film Deposition

MRS Proceedings ◽

10.1557/proc-285-75 ◽

1992 ◽

Vol 285 ◽

Cited By ~ 4

Author(s):

H. Feil ◽

J.S.C. Kools ◽

J. Dieleman

Keyword(s):

Thin Film ◽

Molecular Dynamics ◽

Laser Ablation ◽

Molecular Dynamics Simulations ◽

Film Growth ◽

Thin Film Deposition ◽

Film Deposition ◽

Laser Fluences ◽

Cu Thin Film ◽

Dynamics Simulations

ABSTRACTMolecular dynamics simulations are performed of Cu thin film growth on Cu (111). Ion-Assisted Deposition is simulated by bombarding the substrate with Cu+ ions with a kinetic energy of 80 eV, while 1 eV Cu atoms are used for the simulation of Laser Ablation Deposition. It appears that Ion-Assisted Deposition leads to sputtering, enhanced surface mobility, surface disorder, mixing and rather deep damage. This is discussed in some detail. Laser Ablation Deposition, using laser fluences just above the ablation threshold, does not lead to damage and mixing. Sharper interfaces and more perfect heterostructures and superlattices can be produced using Laser Ablation Deposition.

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Multiple Layers of Copper Thin Films of Alternating Textures

MRS Proceedings ◽

10.1557/proc-750-y9.10 ◽

2002 ◽

Vol 750 ◽

Author(s):

Hanchen Huang ◽

H. L. Wei ◽

H. Y. Liang ◽

C. H. Woo ◽

X. X. Zhang

Keyword(s):

Thin Film ◽

Thin Films ◽

Thin Layer ◽

Texture Evolution ◽

Thin Film Deposition ◽

Film Deposition ◽

Copper Thin Film ◽

Force Microscopy ◽

Anisotropic Elastic ◽

Dynamics Simulations

ABSTRACTIn this paper, we present a preliminary study of texture development during copper thin film deposition. Using direct current (DC) magnetron sputtering technique, we deposit copper films on a SiO2/Si(111) substrate. A thin layer of copper of <111> texture first develops, and another thin layer of <110> ensues. As deposition continues, a third layer of copper of <111> texture forms on the top, leading to a copper thin film of alternating <111> and <110> textures. The multiple layers of copper thin films of alternating textures form during continuous deposition without changing deposition conditions. The film morphology is characterized with scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the texture with X-ray diffraction (XRD). Based on anisotropic elastic analyses and molecular dynamics simulations, we propose a model of texture evolution during the formation of multilayers, attributing the texture evolution to the competition of surface and strain energies.

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Controllable deposition of organic metal halide perovskite films with wafer-scale uniformity by single source flash evaporation

Scientific Reports ◽

10.1038/s41598-020-75764-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Woocheol Lee ◽

Jonghoon Lee ◽

Hyeon-Dong Lee ◽

Junwoo Kim ◽

Heebeom Ahn ◽

...

Keyword(s):

Large Scale ◽

Thin Film Deposition ◽

Film Deposition ◽

Scale Production ◽

Single Source ◽

Flash Evaporation ◽

Large Area ◽

Lead Iodide ◽

Wafer Scale ◽

Evaporation Technique

Abstract Conventional solution-processing techniques such as the spin-coating method have been used successfully to reveal excellent properties of organic–inorganic halide perovskites (OHPs) for optoelectronic devices such as solar cell and light-emitting diode, but it is essential to explore other deposition techniques compatible with large-scale production. Single-source flash evaporation technique, in which a single source of materials of interest is rapidly heated to be deposited in a few seconds, is one of the candidate techniques for large-scale thin film deposition of OHPs. In this work, we investigated the reliability and controllability of the single-source flash evaporation technique for methylammonium lead iodide (MAPbI3) perovskite. In-depth statistical analysis was employed to demonstrate that the MAPbI3 films prepared via the flash evaporation have an ultrasmooth surface and uniform thickness throughout the 4-inch wafer scale. We also show that the thickness and grain size of the MAPbI3 film can be controlled by adjusting the amount of the source and number of deposition steps. Finally, the excellent large-area uniformity of the physical properties of the deposited thin films can be transferred to the uniformity in the device performance of MAPbI3 photodetectors prepared by flash evaporation which exhibited the responsivity of 0.2 A/W and detectivity of 3.82 × 1011 Jones.

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Mechanical transfer of electrochemically grown molybdenum sulfide layers to silicon wafer

Journal of Applied Electrochemistry ◽

10.1007/s10800-021-01570-0 ◽

2021 ◽

Author(s):

Talha Nisar ◽

Torsten Balster ◽

Veit Wagner

Keyword(s):

Thin Films ◽

Large Scale ◽

Thin Film Deposition ◽

Molybdenum Sulfide ◽

Film Deposition ◽

Large Area ◽

Post Annealing ◽

Precursor Material ◽

Coated Film ◽

Underlying Substrate

Abstract Large area MoS2 ultra-thin film deposition is one of the big challenges in the recent years. Electrodeposition provides an opportunity to grow such ultra-thin films on large scale. However, the transfer of the electrochemically grown film is challenging. Standard transfer of those thin films is done by wet etching in which the underlying substrate is etched. In this work, the polymer coated electrodeposited MoS2 films on Au are separated mechanically from the underlying substrate by using ultra-sonication. Collapse of micron-sized bubbles produced by ultra-sonication at the interface of Au and silicon substrate provides enough energy for separation due to their weak adhesion. The Au layer is then removed by standard Au-etchant (K/KI) and the polymer coated film is transferred to a desired substrate. Ammonium tetrathiomolybdate (ATTM) has been used as precursor material for the electrodeposition of the films. Initial electrochemically grown films consist of MoS3 which is reduced to MoS2 by a post-annealing step at 450–900 °C. Obtained films are investigated by AFM, Raman, UV–Vis and XPS. Crystal quality improves by increasing the post-annealing temperature. The thickness of the thinnest film was found to be equivalent to 2 monolayers of MoS2, which is desirable for future electronics. Graphic abstract

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