Local structure order in Pd78Cu6Si16 liquid

Yue, Guoqiang; Zhang, Y.; Sun, Yang; Shen, Bo; Dong, Fuyu; Wang, Z. Y.; Zhang, R. J.; Zheng, Yuanzhou; Kramer, M. J.; Wang, S. Y.; Wang, C. Z.; Ho, Kai‐Ming; Chen, L. Y.

doi:10.1038/srep08277

Cited by 26 publications

(6 citation statements)

References 34 publications

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“…31,41−43 Another important study analyzing pair correlation functions has revealed that Cu holes tend to fill the interstitial sites of the Si network. 44 Despite the fact that considerable progress has been made for crystalline metals and alloys in terms of hydrogen sorption and desorption kinetics, electrochemical studies of the relevant mechanisms in metallic glasses are still very limited. 15,45−50 Here, we elucidate the hydrogen electrosorption mechanism in MGTFs with nanosized thicknesses.…”

Section: Introductionmentioning

confidence: 99%

“…The absorption of hydrogen atoms into Pd and the formation of PdH abs (α- to β-phase transition) results in a volumetric expansion of up to 10.4%. , The critical aspect for the design of Pd-based nanothin films is related to the adjustment of the surface morphology and the glassy structure via composition optimization. For Pd–Si–Cu MG systems, Pd-centered trigonal prism cluster structures capped with 3 half octahedra (9 or 6 Pd atoms surrounding a Si atom) and Cu atoms acting as surrounding atoms of the Pd–Si tetragonal prism were postulated as the main nontranslational structural motifs through analysis of the radial distribution function obtained by neutron diffraction and geometrical structure relaxation simulations. ,− Another important study analyzing pair correlation functions has revealed that Cu holes tend to fill the interstitial sites of the Si network …”

Section: Introductionmentioning

confidence: 99%

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Electrosorption of Hydrogen in Pd-Based Metallic Glass Nanofilms

Sarac

Karazehir

Mühlbacher

et al. 2018

ACS Appl. Energy Mater.

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As an efficient potential hydrogen storage and conversion system, hydrogen electrosorption and evolution mechanisms in Pd-based metallic glass thin films (MGTFs) are investigated. In this study, thin films of 55 nm thickness were deposited by dc magnetron sputtering. The amorphous structure of MGTFs and the atomically smooth interface between the MGTF and substrate were confirmed by transmission electron microscopy, whereas the compositiondependent surface roughness was obtained via atomic force microscopy. The shifts in the broad diffraction maxima for the Si and Cu additions were evaluated by X-ray diffraction. The Pd thin film (PdTF) and MGTF working electrodes were chronoamperometrically saturated in 0.5 M H 2 SO 4 solution. The formation of palladium hydride (PdH x ) in the MGTFs was investigated by X-ray photoelectron spectroscopy. Cyclic voltammograms were subsequently recorded (between −0.2 and 1.4 V) at sweep rates of 0.02 V s −1 . Electrochemical impedance spectroscopy of MGTFs and PdTF was performed in full spectrum including sorption, desorption, and evolution of hydrogen in a conventional three-electrode configuration. Electrochemical circuit modeling provided the relationship between the composition-dependent hydrogen evolution and H absorption/adsorption processes. The adsorption capacitance parameter Y ad corresponding to αand β-hydride formation in the case of Pd 0.79 Si 0.16 Cu 0.05 MGTF is ∼5 times higher than that of the crystalline Pd thin film which is in line with the decrease in the charge-transfer resistance R ct . Addition of Cu disturbs the symmetry of the glass formers, leading to remarkable changes in interfacial hydrogen bonding and diffusion of hydrogen into sublayers. Compared to other Pd-based micron-sized materials, our findings show excellent volumetric hydrogen storage capacity 4 times higher than that of the traditional counterparts of several microns, and 50% higher than the Pd thin films of the same thickness, together with high tunable capacitance, charge-transfer resistance, and diffusivity depending on the glass-forming characteristics of the nanosized MGTF.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrosorption of Hydrogen in Pd-Based Metallic Glass Nanofilms

Sarac

Karazehir

Mühlbacher

et al. 2018

ACS Appl. Energy Mater.

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“…To investigate the effect of oxygen on GFA in Zr 2 Cu alloy, it is essential to understand the underlying topological ordering in this system. The atomistic cluster alignment method provides insight into the average structure in liquid and glass. ,− In this study, for a given temperature and for each type of center atom (i.e., Zr or Cu), 2000 clusters each of which contains a center atom and 15 nearest neighbors are randomly selected from the MD simulation trajectories. The same centered-clusters are then rigidly rotated and translated relative to each other until the overall mean-square distances between different clusters are minimized.…”

Section: Resultsmentioning

confidence: 99%

Effects of Oxygen Impurities on Glass-Formation Ability in Zr₂Cu Alloy

Wang

Yue

et al. 2016

J. Phys. Chem. B

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Using ab initio molecular dynamics simulations, we show that oxygen (O) impurities have a noticeable influence on the glass-formation ability (GFA) in Zr2Cu alloy. Cu-centered icosahedral clusters and Zr-centered Kasper polyhedra are the dominate short-range orders in undercooled Zr2Cu liquid which are most likely to be responsible for the glass formation in Zr2Cu systems. When O is introduced, a Zr octahedron is formed around the O impurity. Most of the Zr atoms in the octahedron also serve as the bridging atoms for cross-linked Kasper polyhedral network, resulting in an O-centered medium range order (MRO) structure. Meanwhile, Cu atoms are moved away from the first shell of O-centered octahedral clusters. With 1 at. % O impurities, the fractions of Zr-centered clusters are less affected, while the increase of ideal icosahedral order and decrease of distorted icosahedral order lead to a more stable atomic structure. This result suggests that a low concentration of O impurities would improve the GFA in Zr2Cu alloy. However, when ∼5 at. % O impurities are included, the ideal icosahedral clusters and Zr-centered Kasper polyhedra are seriously suppressed by the formation of O-centered MRO, which can lead to deterioration of GFA. Our analyses provide useful insight into glass formation behavior in O-doped metallic alloy systems.

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“…This result clearly reveals that local regions with high numbers of icosahedral clusters have small D 2 , while local regions with less icosahedral clusters have large D 2 . Meanwhile, the < 0; 3; 6; 4 > polyhedron, which has been indicated as a distorted fcc structure [28], occupied 7.0%, 6.5%, and 7.2% in G S , G L , and all the atoms, respectively. The < 0; 2; 8; 2 > polyhedron, indicated as a distorted icosahedral cluster, occupied 9.1%, 5.4%, and 6.9% of G S , G L , and all the atoms, respectively.…”

Section: Local Structural Rearrangements In Early Stage Of the Thermamentioning

confidence: 99%

Heterogeneous structural changes correlated to local atomic order in thermal rejuvenation process of Cu-Zr metallic glass

Wakeda

Saida

2019

Science and Technology of Advanced Materials

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In this study, we investigated the atomistic mechanism of structural excitation in a thermal process (thermal rejuvenation) of metallic glass. In a molecular dynamics framework, Cu-Zr metallic glass was rejuvenated by a thermal process composed of an isothermal heat treatment at a temperature above the glass transition temperature T g , followed by fast cooling. Atomistic analyses of the local rearrangement, potential energy, and geometrical structure revealed structural changes correlating to the local atomic order in the rejuvenation process. In the early stage of the heat treatment for thermal rejuvenation, the structural excitation exhibited spatial heterogeneity at the nanometer scale. More-excited regions (i.e., regions with large atomic nonaffine and affine transformations) exhibited low-ordered structures and vice versa, implying that the local structural excitation is significantly correlated with the local atomic order. The structural excitation transitioned from partial to whole as the isothermal process proceeded above T g. Although rejuvenation decreased the ordered structure, the calculation results suggested the formation of newly ordered local structures and newly disordered local structures correlated to local structural excitations and atomic dynamics in the thermal process. These results indicate that the heterogeneous structure evolution of the rejuvenation process induces a redistribution of the local atomic order in the microstructure of metallic glasses.

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Local structure order in Pd78Cu6Si16 liquid

Cited by 26 publications

References 34 publications

Electrosorption of Hydrogen in Pd-Based Metallic Glass Nanofilms

Electrosorption of Hydrogen in Pd-Based Metallic Glass Nanofilms

Effects of Oxygen Impurities on Glass-Formation Ability in Zr₂Cu Alloy

Heterogeneous structural changes correlated to local atomic order in thermal rejuvenation process of Cu-Zr metallic glass

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Local structure order in Pd78Cu6Si16 liquid

Cited by 26 publications

References 34 publications

Electrosorption of Hydrogen in Pd-Based Metallic Glass Nanofilms

Electrosorption of Hydrogen in Pd-Based Metallic Glass Nanofilms

Effects of Oxygen Impurities on Glass-Formation Ability in Zr2Cu Alloy

Heterogeneous structural changes correlated to local atomic order in thermal rejuvenation process of Cu-Zr metallic glass

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Effects of Oxygen Impurities on Glass-Formation Ability in Zr₂Cu Alloy