A Simple EAM Potential for Hydrogen-Selective Palladium Based Membranes for Biomass Derived Syngas Processing

2018 ◽  
Author(s):  
Iyad Hijazi ◽  
Yang Zhang ◽  
Robert Fuller
Keyword(s):  
Elevated Temperatures ◽  
Clean Energy ◽  
Md Simulations ◽  
Miscibility Gap ◽  
Hydrogen Purification ◽  
Embedded Atom ◽  
Energy Technologies ◽  
Renewable Feedstock ◽  
Operational Lifetime ◽  
Eam Potential

Biomass offers the potential to economically produce hydrogen via gasification from an abundant and renewable feedstock. When hydrogen is produced from a biomass gasifier, it is necessary to purify it from syngas streams containing components such as CO, CO2, N2, CH4, and other products. Therefore, a challenge related to hydrogen purification is the development of hydrogen-selective membranes that can operate at elevated temperatures and pressures, provide high fluxes, long operational lifetime, and resistance to poisoning while still maintaining reasonable cost. Palladium based membranes have been shown to be well suited for these types of high-temperature applications and have been widely utilized for hydrogen separation. Palladium’s unique ability to absorb a large quantity of hydrogen can also be applied in various clean energy technologies, like hydrogen fuel cells. In this paper, a fully analytical interatomic Embedded Atom Potential (EAM) for the Pd-H system has been developed, that is easily extendable to ternary Palladium based hydride systems such as Pd-Cu-H and Pd-Ag-H. The new potential has fewer fitting parameters than previously developed EAM Pd-H potentials and is able to accurately predict the cohesive energy, lattice constant, bulk modulus, elastic constants, melting temperature, and the stable Pd-H structures in molecular dynamics (MD) simulations with various hydrogen concentrations. The EAM potential also well predicts the miscibility gap, the segregation of the palladium hydride system into dilute (α) and concentrated (β) phases.

A Simple Palladium Hydride Embedded Atom Method Potential for Hydrogen Energy Applications

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Iyad Hijazi ◽  
Yang Zhang ◽  
Robert Fuller
Keyword(s):  
Elevated Temperatures ◽  
Clean Energy ◽  
Md Simulations ◽  
Miscibility Gap ◽  
Embedded Atom Method ◽  
Hydrogen Energy ◽  
Hydrogen Purification ◽  
Palladium Hydride ◽  
Embedded Atom ◽  
Eam Potential

When hydrogen is produced from a biomass or coal gasifier, it is necessary to purify it from syngas streams containing components such as CO, CO2, N2, CH4, and other products. Therefore, a challenge related to hydrogen purification is the development of hydrogen-selective membranes that can operate at elevated temperatures and pressures, provide high fluxes, long operational lifetime, and resistance to poisoning while still maintaining reasonable cost. Palladium-based membranes have been shown to be well suited for these types of high-temperature applications and have been widely utilized for hydrogen separation. Palladium's unique ability to absorb a large quantity of hydrogen can also be applied in various clean energy technologies, like hydrogen fuel cells. In this paper, a fully analytical interatomic embedded atom method (EAM) potential for the Pd-H system has been developed, that is easily extendable to ternary Palladium-based hydride systems, such as Pd-Cu-H and Pd-Ag-H. The new potential has fewer fitting parameters than previously developed EAM Pd-H potentials and is able to accurately predict the cohesive energy, lattice constant, bulk modulus, elastic constants, melting temperature, and the stable Pd-H structures in molecular dynamics (MD) simulations with various hydrogen concentrations. The EAM potential also well predicts the miscibility gap, the segregation of the palladium hydride system into dilute (α), and concentrated (β) phases.

scholarly journals Molecular Dynamics Study on Deformation Mechanism of Grain Boundaries in Magnesium Crystal: Based on Coincidence Site Lattice Theory

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ken-ichi Saitoh ◽  
Kohei Kuramitsu ◽  
Tomohiro Sato ◽  
Masanori Takuma ◽  
Yoshimasa Takahashi
Keyword(s):  
Molecular Dynamics ◽  
Deformation Mechanism ◽  
Coincidence Site Lattice ◽  
Md Simulations ◽  
Uniaxial Tensile ◽  
High Angle ◽  
Site Lattice ◽  
Embedded Atom ◽  
Significant Difference ◽  
Eam Potential

As for magnesium (Mg) alloys, it has been noted that they are inferior to plastic deformation, but improvement in the mechanical properties by further refinement of grain size has been recently suggested. It means the importance of atomistic view of polycrystalline interface of Mg crystal. In this study, to discuss the deformation mechanism of polycrystalline Mg, atomistic grain boundary (GB) models by using coincidence site lattice (CSL) theory are constructed and are simulated for their relaxed and deformatted structures. First, GB structures in which the axis of rotation is in [11¯00] direction are relaxed at 10 Kelvin, and the GB energies are evaluated. Then, the deformation mechanism of each GB model under uniaxial tensile loading is observed by using the molecular dynamics (MD) method. The present MD simulations are based on embedded atom method (EAM) potential for Mg crystal. As a result, we were able to observe atomistically a variety of GB structures and to recognize significant difference in deformation mechanism between low-angle GBs and high-angle GBs. A close scrutiny is made on phenomena of dislocation emission processes peculiar to each atomistic local structure in high-angle GBs.

scholarly journals Graphene Adhesion Mechanics on Iron Substrates: Insight from Molecular Dynamic Simulations

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 579 ◽  
Author(s):  
Wang ◽  
Jin ◽  
Yang ◽  
Zong ◽  
Peng
Keyword(s):  
Molecular Dynamic ◽  
Surface Engineering ◽  
Graphene Nanosheets ◽  
Pair Potential ◽  
Md Simulations ◽  
Adhesion Energy ◽  
Dynamic Simulations ◽  
Embedded Atom ◽  
Adhesion Mechanics ◽  
Eam Potential

The adhesion feature of graphene on metal substrates is important in graphene synthesis, transfer and applications, as well as for graphene-reinforced metal matrix composites. We investigate the adhesion energy of graphene nanosheets (GNs) on iron substrate using molecular dynamic (MD) simulations. Two Fe–C potentials are examined as Lennard–Jones (LJ) pair potential and embedded-atom method (EAM) potential. For LJ potential, the adhesion energies of monolayer GN are 0.47, 0.62, 0.70 and 0.74 J/m2 on the iron {110}, {111}, {112} and {100} surfaces, respectively, compared to the values of 26.83, 24.87, 25.13 and 25.01 J/m2 from EAM potential. When the number of GN layers increases from one to three, the adhesion energy from EAM potential increases. Such a trend is not captured by LJ potential. The iron {110} surface is the most adhesive surface for monolayer, bilayer and trilayer GNs from EAM potential. The results suggest that the LJ potential describes a weak bond of Fe–C, opposed to a hybrid chemical and strong bond from EAM potential. The average vertical distances between monolayer GN and four iron surfaces are 2.0–2.2 Å from LJ potential and 1.3–1.4 Å from EAM potential. These separations are nearly unchanged with an increasing number of layers. The ABA-stacked GN is likely to form on lower-index {110} and {100} surfaces, while the ABC-stacked GN is preferred on higher-index {111} surface. Our insights of the graphene adhesion mechanics might be beneficial in graphene growing, surface engineering and enhancement of iron using graphene sheets.

Atomistic Investigation on Mechanical Properties of Sn-Ag-Cu Based Nanocrystalline Solder Material

2019 ◽  
Author(s):  
Mohammad Motalab ◽  
Rafsan A. S. I. Subad ◽  
Ayesha Ahmed ◽  
Pritom Bose ◽  
Ratul Paul ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Md Simulations ◽  
Uniaxial Tensile ◽  
Solder Material ◽  
Embedded Atom ◽  
Sac Solder

Abstract In order to develop light weight electrical components, the nano-sized lead free solders have been identified as potential materials to provide better mechanical properties as compared to the conventional solders. Sn–Ag–Cu (SAC) solders have been widely acknowledged as one of the most promising replacements for Sn-Pb solders. In our previous work, mechanical properties of single crystal SAC solder material were investigated through atomistic simulation studies. In this work, the mechanical properties of nanocrystalline SAC305 (nc-SAC305) (96.5Sn-3.0Ag-0.5Cu) solder have been investigated through molecular dynamics (MD) simulations. A set of modified embedded atom method (MEAM) potential parameters have been proposed for nc-SAC solder. Impact of grain size, strain rate and temperature on the uniaxial tensile properties have been studied. The results have revealed an inverse Hall-Petch relationship in the nc-SAC305 material, and grain boundary decohesion is observed as the dominating failure mechanism. The results also suggest that the ultimate tensile strength of SAC305 significantly increases with increasing strain rate. Moreover, increased ductility and decreased ultimate tensile strength are observed at elevated temperatures.

Response of copper nanowires in dynamic tensile deformation

2004 ◽  
Vol 218 (6) ◽  
pp. 599-606 ◽  
Author(s):  
W Liang ◽  
M Zhou
Keyword(s):  
Strain Rate ◽  
Cross Sections ◽  
Tensile Deformation ◽  
Md Simulations ◽  
Dislocation Motion ◽  
Specimen Size ◽  
Copper Nanowires ◽  
Strain Rate Effects ◽  
Embedded Atom ◽  
Eam Potential

Molecular dynamics (MD) simulations with an embedded atom method (EAM) potential are carried out to analyse the size and strain rate effects in the tensile deformation of single-crystal copper nanowires. The cross-sections of the wires are squares with dimensions of between 5 and 20 lattice constants (or 1.8-7.2nm). Deformations under constant strain rates between 1.67 × 107 and 1.67 × 1010s−1 are analysed. It is found that the yield stress decreases with specimen size and increases with loading rate. On the other hand, ductility increases with specimen size and strain rate. The influence of specimen size is due to enhanced opportunities for dislocation motion at larger sizes. The influence of strain rate is due to the dynamic wave effect or phonon drag which impedes the motion of dislocations. The analysis also focuses on the variation in deformation mechanisms with specimen size and strain rate. Slip along alternating (111) planes is observed in small wires, while multiple cross-slips are primarily responsible for the progression of plastic deformation in larger wires. As strain rate is increased, a transition of the deformation mechanism from sequential propagation of slip along well-defined and favourably oriented slip planes to cross-slip, and then to amorphization, is observed.

scholarly journals Synthetic models of hydrogenases based on framework structures containing coordinating P, N-atoms as hydrogen energy electrocatalysts – from molecules to materials

2020 ◽  
Vol 92 (8) ◽  
pp. 1305-1320 ◽  
Author(s):  
Yulia H. Budnikova ◽  
Vera V. Khrizanforova
Keyword(s):  
Fossil Fuels ◽  
High Current Density ◽  
Clean Energy ◽  
Hydrogen Energy ◽  
Energy Technologies ◽  
Highly Active ◽  
Synthetic Materials ◽  
Metal Derivatives ◽  
Metal Organic ◽  
Metal Doped

AbstractNowadays, hydrogen has become not only an extremely important chemical product but also a promising clean energy carrier for replacing fossil fuels. Production of molecular H2 through electrochemical hydrogen evolution reactions is crucial for the development of clean-energy technologies. The development of economically viable and efficient H2 production/oxidation catalysts is a key step in the creation of H2-based renewable energy infrastructure. Intrinsic limitations of both natural enzymes and synthetic materials have led researchers to explore enzyme-induced catalysts to realize a high current density at a low overpotential. In recent times, highly active widespread numerous electrocatalysts, both homogeneous or heterogeneous (immobilized on the electrode), such as transition metal complexes, heteroatom- or metal-doped nanocarbons, metal-organic frameworks, and other metal derivatives (calix [4] resorcinols, pectates, etc.), which are, to one extent or another, structural or functional analogs of hydrogenases, have been extensively studied as alternatives for Pt-based catalysts, demonstrating prospects for the development of a “hydrogen economy”. This mini-review generalizes some achievements in the field of development of new electrocatalysts for H2 production/oxidation and their application for fuel cells, mainly focuses on the consideration of the catalytic activity of M[P2N2]22+ (M = Ni, Fe) complexes and other nickel structures which have been recently obtained.

An embedded-atom method interatomic potential for Pd–H alloys

2008 ◽  
Vol 23 (3) ◽  
pp. 704-718 ◽  
Author(s):  
X.W. Zhou ◽  
J.A. Zimmerman ◽  
B.M. Wong ◽  
J.J. Hoyt
Keyword(s):  
Computational Models ◽  
Mechanical Response ◽  
Hydrogen Diffusion ◽  
Interatomic Potential ◽  
Diffusion Mechanism ◽  
Miscibility Gap ◽  
Embedded Atom Method ◽  
Embedded Atom ◽  
Formidable Challenge ◽  
Embedded Atom Method Potential

Palladium hydrides have important applications. However, the complex Pd–H alloy system presents a formidable challenge to developing accurate computational models. In particular, the separation of a Pd–H system to dilute (α) and concentrated (β) phases is a central phenomenon, but the capability of interatomic potentials to display this phase miscibility gap has been lacking. We have extended an existing palladium embedded-atom method potential to construct a new Pd–H embedded-atom method potential by normalizing the elemental embedding energy and electron density functions. The developed Pd–H potential reasonably well predicts the lattice constants, cohesive energies, and elastic constants for palladium, hydrogen, and PdHx phases with a variety of compositions. It ensures the correct hydrogen interstitial sites within the hydrides and predicts the phase miscibility gap. Preliminary molecular dynamics simulations using this potential show the correct phase stability, hydrogen diffusion mechanism, and mechanical response of the Pd–H system.

Graphene-Based Resonant Sensors for Detection of Ultra-Fine Nanoparticles: Molecular Dynamics and Nonlocal Elasticity Investigations

NANO ◽  
2015 ◽  
Vol 10 (02) ◽  
pp. 1550024 ◽  
Author(s):  
S. Kamal Jalali ◽  
M. Hassan Naei ◽  
Nicola Maria Pugno
Keyword(s):  
Molecular Dynamics ◽  
Nonlocal Elasticity ◽  
Md Simulations ◽  
Small Scale ◽  
Frequency Shifts ◽  
Resonant Sensors ◽  
Embedded Atom ◽  
Metal Metal ◽  
Spring System ◽  
Mass Spring

Application of single layered graphene sheets (SLGSs) as resonant sensors in detection of ultra-fine nanoparticles (NPs) is investigated via molecular dynamics (MD) and nonlocal elasticity approaches. To take into consideration the effect of geometric nonlinearity, nonlocality and atomic interactions between SLGSs and NPs, a nonlinear nonlocal plate model carrying an attached mass-spring system is introduced and a combination of pseudo-spectral (PS) and integral quadrature (IQ) methods is proposed to numerically determine the frequency shifts caused by the attached metal NPs. In MD simulations, interactions between carbon–carbon, metal–metal and metal–carbon atoms are described by adaptive intermolecular reactive empirical bond order (AIREBO) potential, embedded atom method (EAM), and Lennard–Jones (L–J) potential, respectively. Nonlocal small-scale parameter is calibrated by matching frequency shifts obtained by nonlocal and MD simulation approaches with same vibration amplitude. The influence of nonlinearity, nonlocality and distribution of attached NPs on frequency shifts and sensitivity of the SLGS sensors are discussed in detail.

Atomistic Study of Cleavage and Dislocation Emission in NiAl

1994 ◽  
Vol 364 ◽  
Author(s):  
M. Ludwig ◽  
P. Gumbsch
Keyword(s):  
Finite Element ◽  
Mixed Mode ◽  
Crack Tip ◽  
Mode I ◽  
Crack Plane ◽  
Dislocation Emission ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Atomistic Study ◽  
Eam Potential

AbstractThe atomistic processes during fracture of NiAl are studied using a new embedded atom (EAM) potential to describe the region near the crack tip. To provide the atomistically modeled crack tip region with realistic boundary conditions, a coupled finite element - atomistic (FEAt) technique [1] is employed. In agreement with experimental observations, perfectly brittle cleavage is observed for the (110) crack plane. In contrast, cracks on the (100) plane either follow a zig-zag path on (110) planes, or emit dislocations. Dislocation generation is studied in more detail under mixed mode I/II loading conditions.

Technology Focus: Wellbore Tubulars (July 2021)

2021 ◽  
Vol 73 (07) ◽  
pp. 50-50
Author(s):  
Robello Samuel
Keyword(s):  
Geothermal Energy ◽  
Elevated Temperatures ◽  
Clean Energy ◽  
Well Integrity ◽  
The Future ◽  
Geothermal Wells ◽  
Abandoned Wells ◽  
Thermal Simulations ◽  
Technology Focus

How we think about the future of the pipe industry must evolve. How must tubular design and manufacturing change as we transition to clean energy? Geothermal energy is an area that needs attention and, further, needs very specific attention on tubulars. Tubulars are an important component in the construction of geothermal wells, and we must align our requirements for geothermal energy. Some of the main challenges encountered in geothermal wells are corrosion and scaling. Moreover, temperature becomes a major consideration for tubulars, even more so with the temperature excursion during geothermal production. Perhaps the critical aspect in the design of the geothermal wells involves casing selection and design. Beyond manufacturing casing pipes to withstand these problems, considering the manufacturing of other components, such as connections, float collars, and float shoes, also is essential. Thermal expansion and thermal excursion of casings are well-integrity concerns; thus, casing design is important for long-term sustainability of geothermal wells. Apart from thermal simulations, guidelines and software are needed to undergird the designs to withstand not only temperature excursions but also thermomechanical and thermochemical loadings. Engineered nonmetallic casings also provide an alternative solution because they provide the desired strength and corrosion resistance in addition to meeting the goals of sustainability. Undoubtedly, the future of the tubular industry is going to be revitalized. The question now is how we can retrofit existing abandoned wells for this purpose. Recommended additional reading at OnePetro: www.onepetro.org. SPE 199570 - Special Considerations for Well-Tubular Design at Elevated Temperatures by Gang Tao, C-FER Technologies, et al.

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