scholarly journals Grain Boundary Segregation in Pd-Cu-Ag Alloys for High Permeability Hydrogen Separation Membranes

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 81 ◽  
Author(s):  
Ole Løvvik ◽  
Dongdong Zhao ◽  
Yanjun Li ◽  
Rune Bredesen ◽  
Thijs Peters
Keyword(s):  
Boundary Segregation ◽  
Hydrogen Separation ◽  
Atomic Scale ◽  
Grain Structure ◽  
Volume Relaxation ◽  
Lattice Constants ◽  
Separation Membranes ◽  
Starting Point ◽  
Scale Models ◽  
Outer Bounds

Dense metal membranes that are based on palladium (Pd) are promising for hydrogen separation and production due to their high selectivity and permeability. Optimization of alloy composition has normally focused on bulk properties, but there is growing evidence that grain boundaries (GBs) play a crucial role in the overall performance of membranes. The present study provides parameters and analyses of GBs in the ternary Pd-Ag-Cu system, based on first-principles electronic structure calculations. The segregation tendency of Cu, Ag, and vacancies towards 12 different coherent ∑ GBs in Pd was quantified using three different procedures for relaxation of supercell lattice constants, representing the outer bounds of infinitely elastic and stiff lattice around the GBs. This demonstrated a clear linear correlation between the excess volume and the GB energy when volume relaxation was allowed for. The point defects were attracted by most of the GBs that were investigated. Realistic atomic-scale models of binary Pd-Cu and ternary Pd-Cu-Ag alloys were created for the ∑5(210) boundary, in which the strong GB segregation tendency was affirmed. This is a starting point for more targeted engineering of alloys and grain structure in dense metal membranes and related systems.

Design of sustainable V-based hydrogen separation membranes based on grain boundary segregation

2014 ◽  
Vol 39 (23) ◽  
pp. 12031-12044 ◽  
Author(s):  
Won-Seok Ko ◽  
Ju-Young Oh ◽  
Jae-Hyeok Shim ◽  
Jin-Yoo Suh ◽  
Woo Young Yoon ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Segregation ◽  
Hydrogen Separation ◽  
Grain Boundary Segregation ◽  
Separation Membranes

A multi-scale flow analysis in hydrogen separation membranes using a coupled DSMC-SPH method

2012 ◽  
Vol 37 (1) ◽  
pp. 894-902 ◽  
Author(s):  
Jianjun Ye ◽  
Jian Yang ◽  
Jinyang Zheng ◽  
Xianting Ding ◽  
Ieong Wong ◽  
...  
Keyword(s):  
Flow Analysis ◽  
Hydrogen Separation ◽  
Sph Method ◽  
Multi Scale ◽  
Separation Membranes

Atomistic Aspects of Fracture Modelling in the Framework of Continuum Mechanics

1998 ◽  
Vol 538 ◽  
Author(s):  
F. Cleri
Keyword(s):  
Continuum Mechanics ◽  
Constitutive Relations ◽  
Point Of View ◽  
Atomic Scale ◽  
Continuum Models ◽  
Cohesive Law ◽  
Macroscopic Models ◽  
Scale Models ◽  
Level Information ◽  
Set Up

AbstractThe validity and predictive capability of continuum models of fracture rests on basic informations whose origin lies at the atomic scale. Examples of such crucial informations are, e.g., the explicit form of the cohesive law in the Barenblatt model and the shear-displacement relation in the Rice-Peierls-Nabarro model. Modem approaches to incorporate atomic-level information into fracture modelling require to increase the size of atomic-scale models up to millions of atoms and more; or to connect directly atomistic and macroscopic, e.g. finite-elements, models; or to pass information from atomistic to continuum models in the form of constitutive relations. A main drawback of the atomistic methods is the complexity of the simulation results, which can be rather difficult to rationalize in the framework of classical, continuum fracture mechanics. We critically discuss the main issues in the atomistic simulation of fracture problems (and dislocations, to some extent); our objective is to indicate how to set up atomistic simulations which represent well-posed problems also from the point of view of continuum mechanics, so as to ease the connection between atomistic information and macroscopic models of fracture.

From Adatom Migration to Chemical Kinetics: Models for MBE, Mombe and MOCVD

1993 ◽  
Vol 312 ◽  
Author(s):  
D. D. Vvedensky ◽  
T. Shitarat ◽  
P. Smilauer ◽  
T. Kaneko ◽  
A. Zangwill
Keyword(s):  
Experimental Data ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
High Energy ◽  
Atomic Scale ◽  
Basic Model ◽  
Mobile Species ◽  
Local Environments ◽  
Starting Point

AbstractThe application of Monte Carlo simulations to various epitaxial growth methods is examined from the standpoint of incorporating only those kinetics processes that are required to explain experimental data. A basic model for molecular-beam epitaxy (MBE) is first introduced and some of the features that make it suitable for describing atomic-scale processes are pointed out. Extensions of this model for cases where the atomic constituents of the growing surface are delivered in the form of heteroatomic molecules are then considered. The experimental scenarios that is discussed is the homoepitaxy of GaAs(001) using metalorganic molecular-beam epitaxy (MOMBE) with triethylgallium (TEG) and precursors and using MOCVD with trimethylgallium (TMG). For MOMBE, the comparisons between simulations and experiments are based on reflection high-energy electron diffraction intensities, by analogy with comparisons made for MBE, while for metalorganic chemical vapor deposition (MOCVD) the simulations are compared to in situ glancingincidence x-ray scattering measurements. In both of these cases, the inclusion of a second mobile species to represent the precursor together with various rules for the decomposition of this molecule (in terms of rates and local environments) with be shown to provide a useful starting point for explaining the general trends in the experimental data and for further refinements of the model.

scholarly journals A radical polymer for highly efficient solar evaporation and gas separation

2021 ◽  
Author(s):  
Wei Liu ◽  
Ming Yang ◽  
Jing Liu ◽  
Meijia Yang ◽  
Jing Li ◽  
...  
Keyword(s):  
Gas Separation ◽  
Membrane Separation ◽  
Hydrogen Separation ◽  
Solar Irradiation ◽  
Separation Processes ◽  
Highly Efficient ◽  
Separation Membranes ◽  
Gas Separation Membranes ◽  
Transport Channels ◽  
The Impact

Abstract The unique magnetic, electronic and optical features derived from their unpaired electrons have made radical polymers an attractive material platform for various applications. Here, we report solution-processable radical polymer membranes with multi-level porosities and study the impact of free radicals on important membrane separation processes including solar vapor generation, hydrogen separation and CO2 capture. The radical polymer is a supreme light absorber over the full solar irradiation range with sufficient water transport channels, leading to a highly efficient solar evaporation membrane. In addition, the radical polymer with micropores and adjustable functional groups are broad-spectrum gas separation membranes for both hydrogen separation and CO2 capture. First principle calculations indicate that the conjugated polymeric network bearing radicals is more chemically reactive with CO2, compared with H2, N2 and CH4. This is evidenced by a high CO2 permeability in gas separation membranes made of the conjugated radical polymer.

scholarly journals Atomic scale models of Ion implantation and dopant diffusion in silicon

10.2172/12209 ◽  
1999 ◽  
Author(s):  
M Caturla ◽  
M Johnson ◽  
T Lenosky ◽  
B Sadigh ◽  
S K Theiss ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Atomic Scale ◽  
Dopant Diffusion ◽  
Scale Models
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