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Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel 2019 Iowa State University and Ames Laboratory

Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

To assess the energetics of Cu intercalation on defective graphite, the chemical potentials and binding energies for Cu at graphite step edges are calculated for three main configurations: an isolated atom, a chain, and an atom attached to a chain. As expected, for Cu interacting directly with a graphite step edge, the strength of interaction depends on the stability of the step, with Cu binding more strongly at a less-stable step. However, the relationship is reversed when considering binding of a Cu atom attached to a chain. Taken together, these trends mean that if the graphite step is less stable ...


Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel 2019 Iowa State University and Ames Laboratory

Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel

James W. Evans

To assess the energetics of Cu intercalation on defective graphite, the chemical potentials and binding energies for Cu at graphite step edges are calculated for three main configurations: an isolated atom, a chain, and an atom attached to a chain. As expected, for Cu interacting directly with a graphite step edge, the strength of interaction depends on the stability of the step, with Cu binding more strongly at a less-stable step. However, the relationship is reversed when considering binding of a Cu atom attached to a chain. Taken together, these trends mean that if the graphite step is less stable ...


Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel 2019 Iowa State University and Ames Laboratory

Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Patricia A. Thiel

To assess the energetics of Cu intercalation on defective graphite, the chemical potentials and binding energies for Cu at graphite step edges are calculated for three main configurations: an isolated atom, a chain, and an atom attached to a chain. As expected, for Cu interacting directly with a graphite step edge, the strength of interaction depends on the stability of the step, with Cu binding more strongly at a less-stable step. However, the relationship is reversed when considering binding of a Cu atom attached to a chain. Taken together, these trends mean that if the graphite step is less stable ...


On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins 2019 Iowa State University

On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins

Materials Science and Engineering Publications

Laser Engineered Net Shaping (LENS™) was used to produce a compositionally graded Ti-xMo (0 ≤ x ≤ 12 wt %) specimen and nine Ti-15Mo (fixed composition) specimens at different energy densities to understand the composition–processing–microstructure relationships operating using additive manufacturing. The gradient was used to evaluate the effect of composition on the prior-beta grain size. The specimens deposited using different energy densities were used to assess the processing parameters influence the microstructure evolutions. The gradient specimen did not show beta grain size reduction with the Mo content. The analysis from the perspective of the two grain refinement mechanisms based on a ...


Rapid Prototyping Of Reconfigurable Microfluidic Channels In Undercooled Metal Particle-Elastomer Composites, Boyce Chang, Mario Fratzl, Andrea Boyer, Andrew Martin, Henry C. Ahrenholtz, Isabelle De Moraes, Jean-Francis Bloch, Nora M. Dempsey, Martin M. Thuo 2019 Iowa State University

Rapid Prototyping Of Reconfigurable Microfluidic Channels In Undercooled Metal Particle-Elastomer Composites, Boyce Chang, Mario Fratzl, Andrea Boyer, Andrew Martin, Henry C. Ahrenholtz, Isabelle De Moraes, Jean-Francis Bloch, Nora M. Dempsey, Martin M. Thuo

Materials Science and Engineering Publications

Conventional fabrication of microfluidic channels/devices are faced with challenges such as single use channels and/or significant time consumption. We propose a flexible platform for fabricating microfluidic channels simply through indentation on a smart composite—the so-called ST3R (Stiffness tuning through thermodynamic relaxation) composite. The application of ST3R composite allows rapid fabrication of microfluidic channels by hand or with a prefabricated stamp, and precise prototyping of complex designs using a 2D plotter. Indenter geometry, applied stress, filler loading, and number of repeated indentations affect channel dimensions and/or shape. These channels further exhibit; i) Substantial improvement against swelling by ...


Process-Property-Microstructure Relationships In Laser-Powder Bed Fusion Of 420 Stainless Steel., Subrata Deb Nath 2018 University of Louisville

Process-Property-Microstructure Relationships In Laser-Powder Bed Fusion Of 420 Stainless Steel., Subrata Deb Nath

Electronic Theses and Dissertations

Laser-powder bed fusion (L-PBF) is an additive manufacturing technique for fabricating metal components with complex design and customized features. However, only a limited number of materials have been widely studied using L-PBF. AISI 420 stainless steel, an alloy with a useful combination of high strength, hardness, and corrosion resistance, is an example of one such material where few L-PBF investigations have emerged to date. In this dissertation, L-PBF experiments were conducted using 420 stainless steel powders to understand the effects of chemical composition, particle size distribution and processing parameters on ensuing physical, mechanical and corrosion properties and microstructure in comparison ...


Prediction Of Metal Sample Failure From Scanning Electron Microscope Images Using Deep Learning Neural Network, Lawrence Madriaga, Ivan Novikov, Morteza Nurcheshmeh 2018 Western Kentucky University

Prediction Of Metal Sample Failure From Scanning Electron Microscope Images Using Deep Learning Neural Network, Lawrence Madriaga, Ivan Novikov, Morteza Nurcheshmeh

Posters-at-the-Capitol

We present the preliminary results on using a deep learning neural network to predict a metal sample failure based on a set of images obtained with a Scanning Electron Microscope.

Various metal alloy samples were prepared according to ASTM E8/E8M-11 standards for a tensile test. Each sample was prepared for circle grid analysis and then stressed on a tensile machine. Stress and strain values were obtained for each position along the sample by measuring dimensions of each elongated circle. Increasing stress and strain values were found closer to the breakage of the sample with low values found at the ...


Lattice Instability During Solid-Solid Structural Transformations Under A General Applied Stress Tensor: Example Of Si I → Si Ii With Metallization, Nikolai A. Zarkevich, Hao Chen, Valery I. Levitas, Duane D. Johnson 2018 Ames Laboratory

Lattice Instability During Solid-Solid Structural Transformations Under A General Applied Stress Tensor: Example Of Si I → Si Ii With Metallization, Nikolai A. Zarkevich, Hao Chen, Valery I. Levitas, Duane D. Johnson

Aerospace Engineering Publications

The density functional theory was employed to study the stress-strain behavior and elastic instabilities during the solid-solid phase transformation (PT) when subjected to a general stress tensor, as exemplified for semiconducting Si I and metallic Si II, where metallization precedes the PT, so stressed Si I can be a metal. The hydrostatic PT occurs at 76 GPa, while under uniaxial loading it is 11 GPa (3.7 GPa mean pressure), 21 times lower. The Si I → Si II PT is described by a critical value of the phase-field’s modified transformation work, and the PT criterion has only two parameters ...


Comparison Of Salicyl Hydroxamate Adsorption On Rare Earth Phosphates To Oxides And Carbonates, Stephanie Trant 2018 Montana Tech

Comparison Of Salicyl Hydroxamate Adsorption On Rare Earth Phosphates To Oxides And Carbonates, Stephanie Trant

Graduate Theses & Non-Theses

Adsorption behavior of the anionic collector salicyl hydroxamic acid (SHA) on a group of selected rare earth phosphates (REPs) was studied by means of experimental methods and modeling software. These REPs were then compared to rare earth carbonates (RECs) and rare earth oxides (REOs) to develop a trend. A suite of rare earth elements (REE) were studied that included light (LREE) and middle (MREE). Results for heavy (HREE) were inferred. Synthetic phosphate, oxide and carbonate powders of the rare earth elements Lanthanum (La), Cerium (Ce), Europium (Eu) and Dysprosium (Dy) were tested for these studies. Dysprosium phosphate was the only ...


Surface Chemistry And Modelling Of Salicyl Hydroxamic Acid Adsorption At The Surface Of Rare Earth Oxides, Carbonates And Phosphates, Marc F. Sime 2018 Montana Tech

Surface Chemistry And Modelling Of Salicyl Hydroxamic Acid Adsorption At The Surface Of Rare Earth Oxides, Carbonates And Phosphates, Marc F. Sime

Graduate Theses & Non-Theses

The adsorption mechanism of salicyl hydroxamic acid (SHA, C7H7O3N) on rare earth minerals was investigated using two complementary methods: precipitation studies and modelling. Precipitation studies showed that SHA adsorption occurs through a displacement of the hydroxide ion at the surface in an ion exchange mechanism, leading to surface precipitation and/or chemisorption. Surface precipitation predominates in the light rare earth oxides (LREOs), while chemisorption predominates in the heavier REOs. Modelling revealed that adsorption of SHA on the REM surface is dependent upon the orientation of SHA on the surface as well as the distance between rare earth elements sites on ...


Magnetic Properties Of Single Crystalline Itinerant Ferromagnet Alfe2b2, Tey Lamichhane, Li Xiang, Qisheng Lin, Tribhuwan Pandey, David S. Parker, Tae-Hoon Kim, Lin Zhou, Matthew J. Kramer, Sergey L. Bud’ko, Paul C. Canfield 2018 Iowa State University and Ames Laboratory

Magnetic Properties Of Single Crystalline Itinerant Ferromagnet Alfe2b2, Tey Lamichhane, Li Xiang, Qisheng Lin, Tribhuwan Pandey, David S. Parker, Tae-Hoon Kim, Lin Zhou, Matthew J. Kramer, Sergey L. Bud’Ko, Paul C. Canfield

Qisheng Lin

No abstract provided.


Polar Intermetallics Pr5co2ge3 And Pr7co2ge4 With Planar Hydrocarbon‐Like Metal Clusters, Qisheng Lin, Kaiser Aguirre, Scott M. Saunders, Timothy A. Hackett, Yong Liu, Valentin Taufour, Durga Paudyal, Sergey L. Bud’ko, Paul C. Canfield, Gordon J. Miller 2018 Iowa State University and Ames Laboratory

Polar Intermetallics Pr5co2ge3 And Pr7co2ge4 With Planar Hydrocarbon‐Like Metal Clusters, Qisheng Lin, Kaiser Aguirre, Scott M. Saunders, Timothy A. Hackett, Yong Liu, Valentin Taufour, Durga Paudyal, Sergey L. Bud’Ko, Paul C. Canfield, Gordon J. Miller

Qisheng Lin

Planar hydrocarbon‐like metal clusters may foster new insights linking organic molecules with conjugated π–π bonding interactions and inorganic structures in terms of their bonding characteristics. However, such clusters are uncommon in polar intermetallics. Herein, we report two polar intermetallic phases, Pr5Co2Ge3 and Pr7Co2Ge4, both of which feature such planar metal clusters, namely, ethylene‐like [Co2Ge4] clusters plus the concatenated forms and polyacene‐like [Co2Ge2]n ribbons in Pr5Co2Ge3, and 1,2,4,5‐tetramethylbenzene‐like [Co4Ge6] cluster in Pr7Co2Ge4. Just as in the related planar organic structures, these metal–metalloid species are dominated by covalent bonding interactions. Both ...


Grain Boundary Motion Analysis, Jeremy Marquardt, Xiaorong Cai, Marisol Koslowski 2018 Purdue University

Grain Boundary Motion Analysis, Jeremy Marquardt, Xiaorong Cai, Marisol Koslowski

The Summer Undergraduate Research Fellowship (SURF) Symposium

Grain growth is a mechanism to relax residual stresses in thin films. These grains grow out of the thin film surface and are known as whiskers. These whiskers can cause short circuits, so developing scalable and cost effective solutions would increase the reliability and utility of tin electronics. A popular of method of examining tin whiskering is microscopic simulation, as it provides an accurate and cost effective way to predict the consequences of proposed models. Specifically examining the evolution of grain boundaries, this paper aims to present the results of grain boundary motion simulations through a generalized program that streamlines ...


Trends In Pressure-Induced Layer-Selective Half-Collapsed Tetragonal Phases In The Iron-Based Superconductor Family Aeafe(4)As(4), Vladislav Borisov, Paul C. Canfield, Roser Valentí 2018 Goethe University

Trends In Pressure-Induced Layer-Selective Half-Collapsed Tetragonal Phases In The Iron-Based Superconductor Family Aeafe(4)As(4), Vladislav Borisov, Paul C. Canfield, Roser Valentí

Ames Laboratory Accepted Manuscripts

By performing pressure simulations within density functional theory for the family of iron-based superconductors AeAFe4As4 with Ae=Ca, Sr, Ba and A=K, Rb, Cs we predict in these systems the appearance of two consecutive half-collapsed tetragonal transitions at pressures Pc1 and Pc2, which have a different character in terms of their effect on the electronic structure. We find that, similar to previous studies for CaKFe4As4, spin-vortex magnetic fluctuations on the Fe sublattice play a key role for an accurate structure prediction in these materials at zero pressure. We identify clear trends of critical pressures and discuss the relevance of ...


Microstructure And Mechanical Properties Of Selective Laser Melted Superalloy Inconel 625., Md Ashabul Anam 2018 University of Louisville

Microstructure And Mechanical Properties Of Selective Laser Melted Superalloy Inconel 625., Md Ashabul Anam

Electronic Theses and Dissertations

Selective Laser Melting (SLM), a powder based Additive Manufacturing (AM) process, has gained considerable attention in the aerospace, biomedical and automotive industries due to its many potential benefits, such as, capability of fabricating complex three-dimensional components, shortened design to product time, reduction in process steps, component mass reduction and material flexibility. This process uses metallic powder and is capable of fabricating complex structures with excellent microstructure which make SLM not only an improvement over other manufacturing processes but also innovative material processing technology. Inconel 625, a nickel-based super alloy is widely popular in aerospace, chemical and nuclear industries. This alloy ...


Emergent Magnetic Degeneracy In Iron Pnictides Due To The Interplay Between Spin-Orbit Coupling And Quantum Fluctuations, Morten H. Christensen, Peter P. Orth, Brian M. Andersen, Rafael M. Fernandes 2018 University of Minnesota

Emergent Magnetic Degeneracy In Iron Pnictides Due To The Interplay Between Spin-Orbit Coupling And Quantum Fluctuations, Morten H. Christensen, Peter P. Orth, Brian M. Andersen, Rafael M. Fernandes

Physics and Astronomy Publications

Recent experiments in iron pnictide superconductors reveal that, as the putative magnetic quantum critical point is approached, different types of magnetic order coexist over a narrow region of the phase diagram. Although these magnetic configurations share the same wave vectors, they break distinct symmetries of the lattice. Importantly, the highest superconducting transition temperature takes place close to this proliferation of near-degenerate magnetic states. In this Letter, we employ a renormalization group calculation to show that such a behavior naturally arises due to the effects of spin-orbit coupling on the quantum magnetic fluctuations. Formally, the enhanced magnetic degeneracy near the quantum ...


Persistent Correlation Between Superconductivity And Antiferromagnetic Fluctuations Near A Nematic Quantum Critical Point In Fese1−Xsx, P. Wiecki, Khusboo Rana, A. E. Böhmer, Y. Lee, Sergey L. Bud’ko, Paul C. Canfield, Yuji Furukawa 2018 Iowa State University and Ames Laboratory

Persistent Correlation Between Superconductivity And Antiferromagnetic Fluctuations Near A Nematic Quantum Critical Point In Fese1−Xsx, P. Wiecki, Khusboo Rana, A. E. Böhmer, Y. Lee, Sergey L. Bud’Ko, Paul C. Canfield, Yuji Furukawa

Ames Laboratory Accepted Manuscripts

We present 77Se-NMR measurements on FeSe1−xSx samples with sulfur content x=0%, 9%, 15%, and 29%. Twinned nematic domains are observed in the NMR spectrum for all samples except x=29%. The NMR spin-lattice relaxation rate shows that antiferromagnetic (AFM) fluctuations are initially enhanced between x=0% and x=9%, but are strongly suppressed for higher x values. The observed behavior of the AFM fluctuations parallels the superconducting transition temperature Tc in these materials, providing strong evidence for the primary importance of AFM fluctuations for superconductivity, despite the presence of nematic quantum criticality in the FeSe1−xSx system.


Effective Demagnetizing Factors Of Diamagnetic Samples Of Various Shapes, Ruslan Prozorov, Vladimir G. Kogan 2018 Iowa State University and Ames Laboratory

Effective Demagnetizing Factors Of Diamagnetic Samples Of Various Shapes, Ruslan Prozorov, Vladimir G. Kogan

Ames Laboratory Accepted Manuscripts

Effective demagnetizing factors that connect the sample magnetic moment with the applied magnetic field are calculated numerically for perfectly diamagnetic samples of various nonellipsoidal shapes. The procedure is based on calculating the total magnetic moment by integrating the magnetic induction obtained from a full three-dimensional (3D) solution of the Maxwell equations using an adaptive mesh. The results are relevant for superconductors (and conductors in ac fields) when the London penetration depth (or the skin depth) is much smaller than the sample size. Simple but reasonably accurate approximate formulas are given for practical shapes including rectangular cuboids, finite cylinders in axial ...


Non-Hysteretic First-Order Phase Transition With Large Latent Heat And Giant Low-Field Magnetocaloric Effect, F. Guillou, Arjun K. Pathak, Durga Paudyal, Yaroslav Mudryk, F. Wilhelm, A. Rogalev, Vitalij K. Pecharsky 2018 Ames Laboratory

Non-Hysteretic First-Order Phase Transition With Large Latent Heat And Giant Low-Field Magnetocaloric Effect, F. Guillou, Arjun K. Pathak, Durga Paudyal, Yaroslav Mudryk, F. Wilhelm, A. Rogalev, Vitalij K. Pecharsky

Materials Science and Engineering Publications

First-order magnetic transitions (FOMTs) with a large discontinuity in magnetization are highly sought in the development of advanced functional magnetic materials. Isosymmetric magnetoelastic FOMTs that do not perturb crystal symmetry are especially rare, and only a handful of material families, almost exclusively transition metal-based, are known to exhibit them. Yet, here we report a surprising isosymmetric FOMT in a rare-earth intermetallic, Eu2In. What makes this transition in Eu2In even more remarkable is that it is associated with a large latent heat and an exceptionally high magnetocaloric effect in low magnetic fields, but with tiny lattice discontinuities and negligible hysteresis. An ...


Current Progress And Future Challenges In Rare-Earth-Free Permanent Magnets, Jun Cui, Matthew J. Kramer, Lin Zhou, Fei Liu, Alexander Gabay, George Hadjipanayis, Balamurugan Balasubramanian, David Sellmyer 2018 Iowa State University and Ames Laboratory

Current Progress And Future Challenges In Rare-Earth-Free Permanent Magnets, Jun Cui, Matthew J. Kramer, Lin Zhou, Fei Liu, Alexander Gabay, George Hadjipanayis, Balamurugan Balasubramanian, David Sellmyer

Ames Laboratory Accepted Manuscripts

Permanent magnets (PM) are critical components for electric motors and power generators. Key properties of permanent magnets, especially coercivity and remanent magnetization, are strongly dependent on microstructure. Understanding metallurgical processing, phase stability and microstructural changes are essential for designing and improving permanent magnets. The widely used PM for the traction motor in electric vehicles and for the power generator in wind turbines contain rare earth elements Nd and Dy due to their high maximum energy product. Dy is used to sustain NdFeB's coercivity at higher temperature. Due to the high supply risk of rare earth elements (REE) such as ...


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