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3. Ultra-dense hydrogen in small pore hydridic framework

Author

Hyunchul Oh, Nikolay Tumanov, Voraksmy Ban, Xiao Li, Bo Richter, Matthew Hudson, Craig Brown, Gail Iles, Luke Daemen, Dirk Wallacher, Rafael Balderas-Xicohtencatl, Anibal Ramirez-Cuesta, Yongqiang Cheng, Michael Heere, Michael Hirscher, Torben Jensen, and Yaroslav Filinchuk

Abstract

Nanoporous materials have attracted great attention for gas storage, however, high volumetric storage capacity remains still a challenge. Here we investigate a magnesium borohydride framework with small pores and a unique partially negatively-charged non-flat interior for hydrogen and nitrogen uptake using neutron powder diffraction, volumetric gas adsorption, and inelastic neutron scattering. Hydrogen and nitrogen occupy distinctly different adsorption sites in the pores with very different limiting capacities: 2.33 H2 and 0.66 N2 per Mg(BH4)2. Molecular hydrogen is packed extremely dense with about twice the density of liquid hydrogen (144 - 132 g H2/L of pore volume), independently measured by three experimental methods. This study reveals that densely packed hydrogen can be stabilized in small-pore materials at ambient pressures.

Published
2022

4. Advanced Modeling and Simulation Methods for Evaluation of Thermal Neutron Scattering Materials

Author

Chris W. Chapman, Goran Arbanas, Jesse Brown, Kemal Ramić, Yongqiang Cheng, Jiao Lin, Douglas L. Abernathy, Alexander I. Kolesnikov, Matthew B. Stone, Luke Daemen, Anibal Ramirez Cuesta, and Xunxiang Hu

Subjects
General Medicine
Abstract

With the rise of interest in thermal neutron scattering data for advanced reactor, criticality safety, and shielding applications, new experimental data are required for evaluation of new materials or for re-evaluation (or validations) of previously evaluated materials. New experimental data are evaluated in a three-step process: (1) computing the phonon characteristics, (2) computing the dynamic structure factor (DSF) from the data, and (3) using the experimental setup to simulate the experimental data. All three steps have challenges, ranging from the need for a suffciently general material simulation code—a processing code that can compute the corresponding DSF—to having a detailed layout of the instrument/beamline/facility where the data were measured. Whereas phonon characteristics of materials can be computed using various methods (molecular dynamics, density functional theory, etc.), a high-fidelity computation of the DSF and the simulation of the experiment based on the DSF is vital to the accuracy of the evaluation. The latter two steps can be achieved by using the two corresponding code systems developed by instrument scientists at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory: (1) OCLIMAX, a program that calculates the dynamic structure factor from DFT and MD simulation results, and (2) MCViNE, a Monte Carlo neutron ray-tracing program designed to simulate neutron scattering experiments. Recently, polyethylene and yttrium hydride were measured at the Wide Angular-Range Chopper (ARCS) and SEQUOIA instrument stations of the SNS. These experiments are simulated using the density functional theory code, the Cambridge Serial Total Energy Package (CASTEP), to compute its phonon characteristics (eigenvalues/vectors and PDOS), which is then processed using OCLIMAX to yield the DSF, and finally the data at each instrument station are simulated by the MCViNE for comparison to the measured data for evaluation. For comparison to conventional evaluation methods, the scattering data processed from OCLIMAX are compared against those processed from the LEAPR module of NJOY, and the results from MCViNE simulations are compared against previously used simplified beamline models implemented in the Monte Carlo N-Particle (MCNP) code.

Published
2023

5. First Experiments: New Science Opportunities at the Spallation Neutron Source Second Target Station (abridged)

Author

Edmon Begoli, Alan Tennant, Kunlun Hong, John F. Ankner, Christopher B. Stanley, Tomonori Saito, Leighton Coates, Dean A. A. Myles, Lilin He, Christopher A. Tulk, Jesse or Jessy Labbe, Hassina Z. Bilheux, Luke L. Daemen, Christina Hoffmann, Timothy Charlton, Changwoo Do, Eugene Mamontov, Daniel Olds, Katharine Page, Stephen E. Nagler, Nancy J. Dudney, William T. Heller, V.B. Graves, Kenneth W. Herwig, Udaya C. Kalluri, David J. Wesolowski, Wei-Ren Chen, Sudharshan S. Vazhkudai, Sai Venkatesh Pingali, John Katsaras, Antonio M. dos Santos, Andrii Kovalevskyi, Stuart Calder, Matthew J. Cuneo, Jason P. Hodges, Arnab Banerjee, Peter Rosenblad, Michael A. McGuire, Michael R. Fitzsimmons, Andrew Payzant, Ashfia Huq, Lawrence M. Anovitz, Loukas Petridis, Jue Liu, Paul D. Adams, Clarina Dela Cruz, Travis Williams, Anibal Ramirez Cuesta, Zhe Wang, Georg Ehlers, Franz X. Gallmeier, Jay Jay Billings, Al Geist, Bianca Haberl, Alexander I. Kolesnikov, Marshall T. McDonnell, Alexander Johs, Gregory S. Smith, James B. Roberto, Joerg C. Neuefeind, Gabriele Sala, Yongqiang Cheng, Alexandru D. Stoica, Shuo Qian, Tedi-Marie Usher-Ditzian, Hsiu-Wen Wang, Michael Manley, Lee Robertson, Bryan C. Chakoumakos, Jeffrey M. Warren, and Reinhard Boehler

Subjects
Physics, Nuclear engineering, Spallation Neutron Source
Published
2020

6. ICE-MAN the Integrated Computational Environment for Modeling and Analysis for Neutrons at ORNL

Author

Anibal Ramirez-Cuesta, Robert Smith, Eugene Mamontov, and Yongqiang Cheng

Abstract

ICE-MAN is a modeling and analysis workbench for multi-modal studies, designed with neutron science in mind. It streamlines the workflow between different experimental techniques, computer modeling, and databases and reduces the time and learning curve needed to access them thus making a holistic approach to data interpretation more amenable and efficient.

Published
2022

7. First Experiments: New Science Opportunities at the Spallation Neutron Source Second Target Station

Author

Paul Adams, John Ankner, Lawrence (Larry) Anovitz, Arnab Banerjee, Edmon Begoli, Hassina Bilheux, Jay Billings, Reinhard Boehler, Stuart Calder, Bryan Chakoumakos, Timothy Charlton, Wei-Ren Chen, Yongqiang Cheng, Leighton Coates, Matthew Cuneo, Luke Daemen, Clarina Dela Cruz, Changwoo Do, Antonio Moreira dos Santos, Nancy Dudney, Georg Ehlers, Michael Fitzsimmons, Franz Gallmeier, Al Geist II, Van Graves, Bianca Haberl, Lilin He, William Heller, Kenneth Herwig, Jason Hodges, Christina Hoffmann, Kunlun Hong, Ashfia Huq, Alexander Johs, Udaya Kalluri, John Katsaras, Alexander Kolesnikov, Andrii Kovalevskyi, Jesse or Jessy Labbe, Jue Liu, Eugene Mamontov, Michael Manley, Marshall McDonnell, Michael McGuire, Dean Myles, Stephen Nagler, Joerg Neuefeind, Daniel Olds, Katharine Page, Andrew Payzant, Loukas Petridis, Sai Venkatesh Pingali, Shuo Qian, Anibal Ramirez Cuesta, James Roberto, Lee Robertson, Peter Rosenblad, Tomonori Saito, Gabriele Sala, Gregory Smith, Christopher Stanley, Alexandru Stoica, Alan Tennant, Christopher Tulk, Tedi-Marie Usher-Ditzian, Sudharshan Vazhkudai, Jeffrey Warren, Hsiu-Wen Wang, Zhe Wang, David Wesolowski, and Travis Williams

Published
2019

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