scholarly journals Atomic Motion in Crystals from Neutron Diffraction Experiments

2014 ◽  
Vol 70 (a1) ◽  
pp. C1094-C1094
Author(s):  
Bryan Chakoumakos
Keyword(s):  
Neutron Diffraction ◽  
Structural Information ◽  
National Laboratory ◽  
Atomic Displacement ◽  
Department Of Energy ◽  
Temperature Dependent ◽  
Oak Ridge ◽  
Filled Skutterudites ◽  
Atomic Displacement Parameters ◽  
Physical Phenomena

Static or dynamic disorder in crystals causes a decrease in the Bragg peak intensity, and given sufficient number of Bragg peaks over an extended Q-range, atomic displacement parameters (ADPs) can be refined that quantify the intensity reduction due to the mean square displacements of atoms about their average positions. It is becoming increasingly apparent that ADPs constitute equally important structural information as atom positions and site occupancies. Unusual, yet accurately determined, ADPs can provide telltale clues to interesting physical phenomena, e.g., approach of phase transitions, glass-like thermal conductivity, pathways for high ionic conductivity, and a variety positional disorders. Consequently, the demand for high quality ADPs is increasing, owing in part to our desire to understand and tune physical properties of technological materials. Temperature dependent neutron diffraction using single-crystals is perhaps the best possible method to determine precise individual ADPs, yet the number of these studies is surprisingly limited owing to the paucity of neutron sources and dedicated single-crystal neutron diffractometers. ADPs exhibit various temperature dependent behaviors, and can range from harmonic to anharmonic. Examples from work completed and ongoing at Oak Ridge National Laboratory (stephanite, triphylite, amblygonite, petalite, brucite, filled-skutterudites, gas clathrate hydrates, etc.) as well as previously published work will be reviewed with the aim to generalize insights and recommendations. Research conducted at ORNL's High Flux Isotope Reactor and Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.

Designing and Validating Parallel Wire Suspension Bridge Wire Strands for Neutron Diffraction Stress Mapping

2017 ◽  
Vol 905 ◽  
pp. 123-130
Author(s):  
Adrian Brügger ◽  
Seung Yub Lee ◽  
İsmail Cevdet Noyan ◽  
Raimondo Betti
Keyword(s):  
Neutron Diffraction ◽  
Steel Wire ◽  
National Laboratory ◽  
Suspension Bridge ◽  
Galvanized Steel ◽  
Element Analysis ◽  
Parallel Wire ◽  
Oak Ridge ◽  
Contact Points ◽  
Suspension Bridge Cables

Suspension-bridge cables are constructed from strands of galvanized steel wire. They are failure-critical structural members, so a fundamental understanding of their mechanics is imminently important in quantifying suspension bridge safety. The load-carrying capabilities of such strands after local wire failures have been the subject of many theoretical studies utilizing analytical equations and finite-element analysis. Little experimental data, however, exists to validate these models.Over the past five years we have developed a methodology for measuring stress/strain transfer within parallel wire strands of suspension bridge cables using neutron diffraction [1,2]. In this paper we describe the design and verification of parallel cable strands used in our studies. We describe the neutron diffraction strain measurements performed on standard 7-wire and expanded 19-wire models in various configurations at both the Los Alamos National Laboratory Spectrometer for Materials Research at Temperature and Stress (LANL SMARTS) and at the Oak Ridge National Laboratory VULCAN Engineering Materials Diffractometer (ORNL VULCAN). Particular attention is placed on the challenges of aligning and measuring multibody systems with high strain gradients at body-to-body contact points.

Advanced Research and Technology Development Fossil Energy Materials Program

1988 ◽  
Vol 110 (4) ◽  
pp. 670-676
Author(s):  
R. R. Judkins ◽  
R. A. Bradley
Keyword(s):  
Technology Development ◽  
National Laboratory ◽  
Development Program ◽  
Ceramic Composites ◽  
Department Of Energy ◽  
Energy Materials ◽  
Alloy Development ◽  
Fossil Energy ◽  
Oak Ridge ◽  
Research Activities

The Advanced Research and Technology Development (AR&TD) Fossil Energy Materials Program is a multifaceted materials research and development program sponsored by the Office of Fossil Energy of the U.S. Department of Energy. The program is administered by the Office of Technical Coordination. In 1979, the Office of Fossil Energy assigned responsibilities for this program to the DOE Oak Ridge Operations Office (ORO) as the lead field office and Oak Ridge National Laboratory (ORNL) as the lead national laboratory. Technical activities on the program are divided into three research thrust areas: structural ceramic composites, alloy development and mechanical properties, and corrosion and erosion of alloys. In addition, assessments and technology transfer are included in a fourth thrust area. This paper provides information on the structure of the program and summarizes some of the major research activities.

scholarly journals Preface: Special Topic on Advances in Modern Neutron Diffraction at Oak Ridge National Laboratory

2018 ◽  
Vol 89 (9) ◽  
pp. 092601
Author(s):  
Katharine Page ◽  
Bianca Haberl ◽  
Leighton Coates ◽  
Matthew Tucker
Keyword(s):  
Neutron Diffraction ◽  
National Laboratory ◽  
Special Topic ◽  
Oak Ridge ◽  
Oak Ridge National Laboratory

Development of Testing Methodologies for Onsite Radioactive Material Storage Containers

2008 ◽  
Author(s):  
Matthew R. Feldman
Keyword(s):  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Nuclear Material ◽  
Department Of Energy ◽  
Radioactive Material ◽  
Development Effort ◽  
Nuclear Facilities ◽  
Los Alamos National Laboratory ◽  
Oak Ridge ◽  
Transportation Technologies

Based on a recommendation from the Defense Nuclear Facilities Safety Board, the Department of Energy (DOE) Office of Nuclear Safety Policy and Assistance (HS-21) has recently issued DOE Manual 441.1-1 entitled Nuclear Material Packaging Manual. This manual provides guidance regarding the use of non-engineered storage media for all special nuclear material throughout the DOE complex. As part of this development effort, HS-21 has funded the Oak Ridge National Laboratory (ORNL) Transportation Technologies Group (TTG) to develop and demonstrate testing protocols for such onsite containers. ORNL TTG to date has performed preliminary tests of representative onsite containers from Lawrence Livermore National Laboratory and Los Alamos National Laboratory. This paper will describe the testing processes that have been developed.

Neutron macromolecular crystallography

2018 ◽  
Vol 2 (1) ◽  
pp. 39-55 ◽  
Author(s):  
Matthew P. Blakeley ◽  
Alberto D. Podjarny
Keyword(s):  
Neutron Diffraction ◽  
Fluorescent Proteins ◽  
National Laboratory ◽  
Direct Determination ◽  
Drug Binding ◽  
Proton Accelerator ◽  
Biological Macromolecules ◽  
Macromolecular Crystallography ◽  
Neutron Sources ◽  
Oak Ridge

Neutron diffraction techniques permit direct determination of the hydrogen (H) and deuterium (D) positions in crystal structures of biological macromolecules at resolutions of ∼1.5 and 2.5 Å, respectively. In addition, neutron diffraction data can be collected from a single crystal at room temperature without radiation damage issues. By locating the positions of H/D-atoms, protonation states and water molecule orientations can be determined, leading to a more complete understanding of many biological processes and drug-binding. In the last ca. 5 years, new beamlines have come online at reactor neutron sources, such as BIODIFF at Heinz Maier-Leibnitz Zentrum and IMAGINE at Oak Ridge National Laboratory (ORNL), and at spallation neutron sources, such as MaNDi at ORNL and iBIX at the Japan Proton Accelerator Research Complex. In addition, significant improvements have been made to existing beamlines, such as LADI-III at the Institut Laue-Langevin. The new and improved instrumentations are allowing sub-mm3 crystals to be regularly used for data collection and permitting the study of larger systems (unit-cell edges >100 Å). Owing to this increase in capacity and capability, many more studies have been performed and for a wider range of macromolecules, including enzymes, signalling proteins, transport proteins, sugar-binding proteins, fluorescent proteins, hormones and oligonucleotides; of the 126 structures deposited in the Protein Data Bank, more than half have been released since 2013 (65/126, 52%). Although the overall number is still relatively small, there are a growing number of examples for which neutron macromolecular crystallography has provided the answers to questions that otherwise remained elusive.

scholarly journals Multilayer Diffraction Reveals That Colloidal Superlattices Approach the Structural Perfection of Single Crystals

2020 ◽  
Author(s):  
Stefano Toso ◽  
Dmitry Baranov ◽  
Davide Altamura ◽  
Francesco Scattarella ◽  
Jakob Dahl ◽  
...  
Keyword(s):  
Structural Information ◽  
Accurate Determination ◽  
Diffraction Method ◽  
Atomic Displacement ◽  
Interparticle Spacing ◽  
X Rays ◽  
Structural Perfection ◽  
Fitting Algorithm ◽  
Atomic Displacement Parameters

Colloidal superlattices are fascinating materials made of ordered nanocrystals, yet they are rarely called “atomically precise.” That is unsurprising, given how challenging it is to quantify the degree of structural order in these materials. However, once that order crosses a certain threshold, constructive interference of X-rays diffracted by the nanocrystals dominates the diffraction pattern, offering a wealth of structural information. By treating nanocrystals as scattering sources forming a self-probing interferometer, we developed a multilayer diffraction method that enabled the accurate determination of nanocrystal size, interparticle spacing, and their fluctuations for samples of self-assembled CsPbBr<sub>3</sub> and PbS nanomaterials. The average nanocrystal displacement of 0.32-1.4 Å in the studied superlattices provides a figure of merit for their structural perfection and approaches the atomic displacement parameters found in traditional crystals. The method requires a laboratory-grade diffractometer and an open-source fitting algorithm for data analysis, providing a competitive alternative to resource-intensive synchrotron experiments.

scholarly journals Conceptual Design of a MEDE Treatment System for Sodium Bonded Fuel

2008 ◽  
Author(s):  
Carl E. Baily ◽  
Karen A. Moore ◽  
Collin J. Knight ◽  
Peter B. Wells ◽  
Paul J. Petersen ◽  
...  
Keyword(s):  
Spent Nuclear Fuel ◽  
National Laboratory ◽  
Department Of Energy ◽  
Test Facility ◽  
Evaporation Chamber ◽  
Oak Ridge ◽  
Uranium Fuel ◽  
Fuel Assemblies ◽  
Metal Fuel ◽  
Enriched Uranium

Unirradiated sodium bonded metal fuel and casting scrap material containing highly enriched uranium (HEU) is stored at the Materials and Fuels Complex (MFC) on the Idaho National Laboratory (INL). This material, which includes intact fuel assemblies and elements from the Fast Flux Test Facility (FFTF) and Experimental Breeder Reactor-II (EBR-II) reactors, as well as scrap material from the casting of these fuels, has no current use under the terminated reactor programs for both facilities. The Department of Energy (DOE), under the Sodium-Bonded Spent Nuclear Fuel Treatment Record of Decision (ROD), has determined that this material could be prepared and transferred to an off-site facility for processing and eventual fabrication of fuel for commercial nuclear reactors. A plan is being developed to prepare, package, and transfer this material to the DOE HEU Disposition Program Office (HDPO), located at the Y-12 National Security Complex in Oak Ridge, Tennessee. Disposition of the sodium bonded material will require separating the elemental sodium from the metallic uranium fuel. A sodium distillation process known as MEDE (Melt-Drain-Evaporate), will be used for the separation process. The casting scrap material needs to be sorted to remove any foreign material or fines that are not acceptable to the HDPO program. Once all elements have been cut and loaded into baskets, they are then loaded into an evaporation chamber as the first step in the MEDE process. The chamber will be sealed and the pressure reduced to approximately 200 mtorr. The chamber will then be heated as high as 650 °C, causing the sodium to melt and then vaporize. The vapor phase sodium will be driven into an outlet line where it is condensed and drained into a receiver vessel. Once the evaporation operation is complete, the system is de-energized and returned to atmospheric pressure. This paper describes the MEDE process as well as a general overview of the furnace systems, as necessary, to complete the MEDE process.

scholarly journals Calculation of Metallocene Ionization Potentials via Auxiliary Field Quantum Monte Carlo: Towards Benchmark Quantum Chemistry for Transition Metals

2021 ◽  
Author(s):  
Benjamin Rudshteyn ◽  
John Weber ◽  
Dilek Coskun ◽  
Pierre A. Devlaminck ◽  
Shiwei Zhang ◽  
...  
Keyword(s):  
Quantum Monte Carlo ◽  
National Science Foundation ◽  
National Laboratory ◽  
Computer Time ◽  
Department Of Energy ◽  
National Science Foundation Grant ◽  
Science And Engineering ◽  
Oak Ridge ◽  
National Science ◽  
The U.S

Main Document<div>Supporting Information</div><div>XYZ Coordinates of Structures</div><div><br></div><div><div> An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725.</div><div>This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562. In particular, we used San Diego Computing Center's Comet resources under grant number TG-CHE190007 and allocation ID COL151.</div><div>The Flatiron Institute is a division of the Simons Foundation.</div></div>

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