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Search Publications by: Andrew J Allen (Fed)

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Displaying 1 - 25 of 128

In situ Probing of Interfacial Roughness and Transient Phases During Ceramic Cold Sintering Process

October 15, 2023
Fan Zhang, Russell Maier, Igor Levin, Andrew J. Allen, Jun-Sang Park, Peter Kenesei, Ivan Kuzmenko, Jan Ilavsky, Pete Jemian
The ceramic cold sintering process (CSP) offers an eco-friendly approach to producing fully dense ceramics at low temperatures. However, an incomplete mechanistic understanding hinders its optimization and widespread adoption. In this study, we analyze the

Dynamic structural and microstructural responses of a metal organic framework type material to carbon dioxide under dual gas flow and supercritical conditions

February 1, 2023
Andrew J. Allen, Eric J. Cockayne, Winnie Wong-Ng, Jeffrey Culp, Ivan Kuzmenko
The structural and microstructural responses of a model metal-organic framework (MOF) material, Ni(3-Methy-4,4'-bipyridine)[Ni(CN)4] (Ni-BpyMe or PICNIC 21), to CO2 adsorption and desorption are reported for in situ small-angle X-ray scattering (SAXS) and

Reproducible Sorbent Materials Foundry for Carbon Capture at Scale

September 22, 2022
Austin McDannald, Howie Joress, Brian DeCost, Avery Baumann, A. Gilad Kusne, Kamal Choudhary, Taner N. Yildirim, Daniel Siderius, Winnie Wong-Ng, Andrew J. Allen, Christopher Stafford, Diana Ortiz-Montalvo
We envision an autonomous sorbent materials foundry (SMF) for rapidly evaluating materials for direct air capture of carbon dioxide ( CO2), specifically targeting novel metal organic framework materials. Our proposed SMF is hierarchical, simultaneously

On the Future of Scientific Publication

October 12, 2021
Peter Strickland, Andrew J. Allen
We give a brief review of the rapidly changing landscape for scientific publication, especially in regard to scientific archival journal publication. Some of the many challenges and opportunities are outlined. These include the various forms of open access

Volumetric and Size Characterization of Void Morphologies in Thermally Sprayed Metallic Deposits Using Scattering Techniques

October 12, 2021
T Keller, W. Wagner, J Ilavsky, Andrew J. Allen, N Margadant, S Siegmann, J Pisacka, G Barbezat, R Enzl
The complex void microstructure of thermally sprayed deposits may be approximated by three major void syste(interlamellar pores, intralamellar cracks, and volumetric globular voids), each with different volume fractions,anisotropies, sizes and shapes. This

Solid-State Transformation of an Additive Manufactured Inconel 625 Alloy at 700 degC

September 23, 2021
Fan Zhang, Jan Ilavsky, Greta Lindwall, Mark R. Stoudt, Lyle E. Levine, Andrew J. Allen
Inconel 625, a nickel-based superalloy, has drawn much attention in the emerging field of additive manufacturing (AM) because of its excellent weldability and resistance to hot cracking. The extreme processing condition of AM often introduces enormous

An open-access future for Journal of Synchrotron Radiation - an Editorial from the Main Editors and IUCr Journals Editor-in-Chief

September 1, 2021
Kristina Kvashnina, Yoshiyuki Amemiya, Dibyendu Bhattacharyya, Ingolf Lindau, Andrew J. Allen
This is an Editorial for the Journal of Synchrotron Radiation (JSR) to inform all readers, authors and supporters about the coming transition of the journal to become fully open access. All papers submitted to JSR after 1 October 2021, will be for open

Density Functional Theory Study of the Structure of the Pillared Hofmann compound Ni(3-Methy-4,4'-bipyridine)[Ni(CN)4] (Ni-BpyMe or PICNIC 21)

July 14, 2021
Eric J. Cockayne, Winnie Wong-Ng, Yu-Sheng Chen, Jeffrey T. Culp, Andrew J. Allen
We use dispersion-corrected density functional theory (DFT) to investigate the structure of the pillared Hofmann compound Ni(3-Methy-4,4'-bipyridine)[Ni(CN)4] (NiBpyMe for short, or PICNIC 21). We model the disorder found in experimental X-ray structure

Synthesis, Structural and Sorption Characterization of a Hofmann Compound, Ni(3-Methy-4,4'-bipyridine)[Ni(CN)4]

March 6, 2021
Winnie Wong-Ng, Jeffrey T. Culp, Daniel Siderius, Yu-Sheng Chen, S. Y. G. Wang, Andrew J. Allen, Eric J. Cockayne
Crystal structure of the guest-free Ni(CN)4-based metal organic framework Ni(3-Methy-4,4'-bipyridine)[Ni(CN)4] (nicknamed Ni-BpyMe(A)), was determined to be orthorhombic, Pmma, a= 12.6025(4) Å, b=7.3324(3) Å, c=11.3095(4) Å, V=1045.07 (2) Å3 and Z=2

In situ characterization of ceramic cold sintering by small-angle scattering

January 1, 2021
Andrew J. Allen, Igor Levin, Russell Maier, Suzanne E. Witt, Fan Zhang, Ivan Kuzmenko
The first in situ characterization of the pore morphology evolution during the cold sintering process (CSP) is presented using small-angle X-ray scattering methods. For practical reasons, measurements have been made on a model system, KH2PO4 (KDP). The

Materials Research & Measurement Needs for Ceramics Additive Manufacturing

November 1, 2020
Andrew J. Allen, Igor Levin, Suzanne E. Witt
We report on a recent workshop dedicated to additive manufacturing (AM) of ceramics that was held at the National Institute of Standards and Technology (NIST) in November 2019. This two- day all-invited meeting brought together experts from industry

Early stage nucleation in barium disilicate glass

August 1, 2020
Ling Cai, Randall E. Youngman, David E. Baker, Aram Rezikyan, Minghui Zhang, Bryan Wheaton, Indrajit Dutta, Bruce G. Aitken, Andrew J. Allen
Early stage nucleation in silicate glasses is often evidenced by formation of nanosized regions that are stoichiometrically different from the surrounding matrix. The structural origin of these early stage nucleation sites is of great interest in gaining a

Outcomes and Conclusions from the 2018 AM-Bench Measurements, Challenge Problems, Modeling Submissions, and Conference

February 13, 2020
Lyle E. Levine, Brandon M. Lane, Jarred C. Heigel, Kalman D. Migler, Mark R. Stoudt, Thien Q. Phan, Richard E. Ricker, Maria Strantza, Michael R. Hill, Fan Zhang, Jonathan E. Seppala, Edward J. Garboczi, Erich D. Bain, Daniel Cole, Andrew J. Allen, Jason C. Fox, Carelyn E. Campbell
The Additive Manufacturing Benchmark Test Series (AM-Bench) was established to provide rigorous measurement test data for validating additive manufacturing (AM) simulations for a broad range of AM technologies and material systems. AM-Bench includes

Utica Shale Reactivity: CO2 Induced Pore Scale Changes in the Fracture Network and Matrix

January 3, 2020
Angela Goodman, Sean Sanguinito, Sittichai Natesakhawat, Patricia Cvetic, Barbara Kutchko, Andrew J. Allen
The Utica Shale is expected to be a substantial fossil fuel resource in the future. Currently, 663.5 billion cubic feet of natural gas and oil are being produced from the Utica in Eastern Ohio. In this work, we examined the Utica Shale and its reactivity

Phase Fraction and Evolution of Additively Manufactured 15-5 Stainless Steel and Inconel 625 AM- Benchmark Artifacts

August 5, 2019
Fan Zhang, Lyle E. Levine, Andrew J. Allen, Sandra A. Young, Maureen E. Williams, Mark R. Stoudt, Kil-Won Moon, Jarred C. Heigel, Jan Ilavsky
A proper understanding of the structure and microstructure of additive manufactured (AM) alloys is essential not only to the prediction and assessment of their material properties, but also to the validation and verification of computer models essential to

Disordered Heterogeneous Materials

July 1, 2019
Andrew J. Allen
This chapter describes the use of diffraction-based methods to characterize amorphous or disordered heterogeneous materials. Quantitative materials microstructure characterization using small-angle scattering methods is emphasized. While these techniques

Structural basis of CO2 adsorption in a flexible metal organic framework material

March 4, 2019
Andrew J. Allen, Winnie K. Wong-Ng, Eric J. Cockayne, Jeffrey T. Culp, Christopher Matranga
This paper reports the structural basis of CO2 adsorption in a representative model flexible metal organic framework (MOF) material, Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN)4] (NiBpene or PICNIC-60). NiBpene exhibits a CO2 sorption isotherm with

Simulation of TTT curves for additively manufactured Inconel 625

January 1, 2019
Carelyn E. Campbell, Greta Lindwall, Eric Lass, Fan Zhang, Mark R. Stoudt, Andrew J. Allen, Lyle E. Levine
The ability to use common computational thermodynamic and kinetic tools to study the microstructure evolution in Inconel 625 (IN625) manufactured using the additive manufacturing (AM) technique of laser powder-bed fusion is evaluated. Solidification