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Pugliese A, Shyam B, Repa GM, Nguyen AH, Mehta A, Webb III EB, Fredin LA, Strandwitz NC. Atomic-Layer-Deposited Aluminum Oxide Thin Films Probed with X-ray Scattering and Compared to Molecular Dynamics and Density Functional Theory Models. ACS Omega 2022; 7:41033-41043. [PMID: 36406558 PMCID: PMC9670265 DOI: 10.1021/acsomega.2c04402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
A better understanding of amorphous aluminum oxide's structure and electronic properties is obtained through combined experimental and computational approaches. Grazing incidence X-ray scattering measurements were carried out on aluminum oxide thin films grown using thermal atomic layer deposition. The corresponding pair distribution functions (PDFs) showed structures similar to previously reported PDFs of solid-state amorphous alumina and molten alumina. Structural models based on crystalline alumina polymorphs (PDFgui) and amorphous alumina (molecular dynamics, MD) were examined for structural comparisons to the experimental PDF data. Smaller MD models were optimized and verified against larger models to allow for quantum chemical electronic structure calculations. The electronic structure of the amorphous alumina models yields additional insight into the band structure and electronic defects present in amorphous alumina that are not present in crystalline samples.
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Affiliation(s)
- Anthony Pugliese
- Materials
Science and Engineering Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
| | - Badri Shyam
- Xerion
Advanced Battery Corporation, Kettering, Ohio 45420, USA
| | - Gil M. Repa
- Chemistry
Department, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Anh Hung Nguyen
- Mechanical
Engineering and Mechanics Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
| | - Apurva Mehta
- SLAC
National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Edmund B. Webb III
- Mechanical
Engineering and Mechanics Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
| | - Lisa A. Fredin
- Chemistry
Department, Lehigh University, Bethlehem, Pennsylvania 18015, USA
| | - Nicholas C. Strandwitz
- Materials
Science and Engineering Department, Lehigh
University, Bethlehem, Pennsylvania 18015, USA
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2
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Wilke SK, Alderman OLG, Benmore CJ, Neuefeind J, Weber R. Octahedral oxide glass network in ambient pressure neodymium titanate. Sci Rep 2022; 12:8258. [PMID: 35585110 DOI: 10.1038/s41598-022-12342-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/06/2022] [Indexed: 12/05/2022] Open
Abstract
Rare-earth titanates form very fragile liquids that can be made into glasses with useful optical properties. We investigate the atomic structure of 83TiO2-17Nd2O3 glass using pair distribution function (PDF) analysis of X-ray and neutron diffraction with double isotope substitutions for both Ti and Nd. Six total structure factors are analyzed (5 neutron + 1 X-ray) to obtain complementary sensitivities to O and Ti/Nd scattering, and an empirical potential structure refinement (EPSR) provides a structural model consistent with the experimental measurements. Glass density is estimated as 4.72(13) g cm−3, consistent with direct measurements. The EPSR model indicates nearest neighbor interactions for Ti-O at \documentclass[12pt]{minimal}
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\begin{document}$$\overline{r}_{TiO}$$\end{document}r¯TiO = 1.984(11) Å with coordination of \documentclass[12pt]{minimal}
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\begin{document}$$n_{TiO}$$\end{document}nTiO = 5.72(6) and for Nd-O at \documentclass[12pt]{minimal}
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\begin{document}$$\overline{r}_{NdO}$$\end{document}r¯NdO = 2.598(22) Å with coordination of \documentclass[12pt]{minimal}
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\begin{document}$$n_{NdO}$$\end{document}nNdO = 7.70(26), in reasonable agreement with neutron first order difference functions for Ti and Nd. The titanate glass network comprises a mixture of distorted Ti-O5 and Ti-O6 polyhedra connected via 71% corner-sharing and 23% edge-sharing. The O-Ti coordination environments include 15% nonbridging O-Ti1, 51% bridging O-Ti2, and 32% tricluster O-Ti3. This structure is highly unusual for oxide glasses melt-quenched at ambient pressure, as it consists of Ti-Ox predominantly in octahedral (with nearly no tetrahedral) coordination.
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Benmore CJ, González GB, Alderman OLG, Wilke SK, Yarger JL, Leinenweber K, Weber JKR. Hard x-ray methods for studying the structure of amorphous thin films and bulk glassy oxides. J Phys Condens Matter 2021; 33:194001. [PMID: 33540391 DOI: 10.1088/1361-648x/abe352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 02/04/2021] [Indexed: 06/12/2023]
Abstract
High-energy photon diffraction minimizes many of the corrections associated with laboratory x-ray diffractometers, and enables structure factor measurements to be made over a wide range of momentum transfers. The method edges us closer toward an ideal experiment, in which coordination numbers can be extracted without knowledge of the sample density. Three case studies are presented that demonstrate new hard x-ray methods for studying the structure of glassy and amorphous materials. First, the methodology and analysis of high-energy grazing incidence on thin films is discussed for the case of amorphous In2O3. The connectivity of irregular InO6polyhedra are shown to exist in face-, edge- and corner-shared configurations in the approximate ratio of 1:2:3. Secondly, the technique of high-energy small and wide angle scattering has been carried out on laser heated and aerodynamically levitated samples of silica-rich barium silicate (20BaO:80SiO2), from the single phase melt at 1500oC to the phase separated glass at room temperature. Based on Ba-O coordination numbers of 6 to 7, it is argued that the although the potential of Ba is ionic, it is weak enough to cause the liquid-liquid immiscibility to become metastable. Lastly, high-energy small and wide angle scattering has also been applied to high water content (up to 12 wt.%) samples of hydrous SiO2glass quenched from 1500oC at 4 GPa. An increase of Si1-O2correlations at 4.3 Å is found to be consistent with an increase in the population of three-membered SiO4rings at the expense of larger rings.
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Affiliation(s)
- C J Benmore
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, United States of America
- Arizona State University, Tempe, AZ 85287, United States of America
| | - G B González
- Department of Physics, DePaul University, Chicago, Illinois 60614, United States of America
| | - O L G Alderman
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - S K Wilke
- Materials Development, Inc., Evanston, IL 60202, United States of America
| | - J L Yarger
- Arizona State University, Tempe, AZ 85287, United States of America
| | - K Leinenweber
- Arizona State University, Tempe, AZ 85287, United States of America
| | - J K R Weber
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, United States of America
- Materials Development, Inc., Evanston, IL 60202, United States of America
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Ge X, Hu Q, Yang F, Xu J, Han Y, Lai P, Qin J, Li J. Anomalous structure transition in undercooled melt regulates polymorphic selection in barium titanate crystallization. Commun Chem 2021; 4:27. [PMID: 36697544 DOI: 10.1038/s42004-021-00462-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 02/01/2021] [Indexed: 01/28/2023] Open
Abstract
The crystallization processes of titanates are central to the fabrication of optical and electrical crystals and glasses, but their rich polymorphism is not fully understood. Here, we show when and how polymorphic selection occurs during the crystallization of barium titanate (BaTiO3, BT) using in situ high energy synchrotron X-ray diffraction and ab initio molecular dynamic simulation. An anomalous structure transition is found in molten BT during cooling across the cubic-hexagonal transition temperature, which enables nucleation selection of BT by manipulating the undercooling: a cubic phase is preferred if nucleation is triggered at large undercooling, whereas a hexagonal phase is promoted at small undercooling. We further reveal that the nucleation selection between the cubic and the hexagonal phase is regulated by the intrinsic structure property of the melt, in particular, the degree of polymerization between Ti-O polyhedra. These findings provide an innovative perspective to link the polymorphic crystallization to the non-isomorphic structure transition of the melt beyond the conventional cognition of structural heredity.
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Agca C, Neuefeind JC, McMurray JW, Liu J, Benmore CJ, Weber RJK, Navrotsky A. In Situ High-Temperature Synchrotron Diffraction Studies of (Fe,Cr,Al) 3O 4 Spinels. Inorg Chem 2020; 59:5949-5957. [PMID: 32320222 DOI: 10.1021/acs.inorgchem.9b03726] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The modeling of a loss-of-coolant-accident scenario involving nuclear fuels with FeCrAl cladding materials in consideration to replace a Zircaloy requires knowledge of the thermodynamics of oxidized structures. At temperatures higher than 1500 °C, oxidation of FeCrAl alloys forms (Fe,Cr,Al)3O4 spinels. In situ high-energy X-ray diffraction in a conical nozzle levitator installed at beamline 6-ID-D of the APS was used to study the structural evolution of the oxides as a function of the temperature. Single-phase (spinel) and multiphase (spinel-corundum-FeAlO3) regions are mapped as a function of the temperature for three different compositions of FeCrAl oxidation products. The thermal expansion coefficients and cation distribution in the spinel structure have been refined. The temperature at which complete melting of the fuel cladding is expected has been determined by the liquidus temperatures of the oxidized products to be between 1657 and 1834 °C in a 20% O2/Ar atmosphere using the cooling trace method. The liquidus temperature increases with increasing Al and Cr content in the spinel phase.
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Affiliation(s)
- Can Agca
- Peter A. Rock Thermochemistry Laboratory, University of California-Davis (UC Davis), Davis, California 95616, United States.,Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
| | - Jörg C Neuefeind
- Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
| | - Jake W McMurray
- Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
| | - Jue Liu
- Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee 37831, United States
| | - Chris J Benmore
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), 9700 South Cass Avenue, Argonne, Illinois 60439, United States
| | - Richard J K Weber
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), 9700 South Cass Avenue, Argonne, Illinois 60439, United States.,Materials Development, Inc., Arlington Heights, Illinois 60004, United States
| | - Alexandra Navrotsky
- Peter A. Rock Thermochemistry Laboratory, University of California-Davis (UC Davis), Davis, California 95616, United States.,Center for Materials of the Universe, School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
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Alderman OLG, Benmore CJ, Neuefeind J, Tamalonis A, Weber R. Molten barium titanate: a high-pressure liquid silicate analogue. J Phys Condens Matter 2019; 31:20LT01. [PMID: 30790768 DOI: 10.1088/1361-648x/ab0939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The structure of molten BaTiO3 has been measured using laser heating, aerodynamic levitation and a combination of neutron diffraction with Ti isotope substitution, x-ray diffraction and spectroscopy. All measurements indicate a Ti-O coordination of n TiO = 4.4(2), far lower than the perovskite or hexagonal crystalline forms. However, n TiO > 4 suggests structural analogy with molten silicates at high pressures. We introduce methodology for ascertaining such analogies and demonstrate similarity with molten CaSiO3 at upper mantle pressures circa 5 GPa. Although some topological differences exist, we propose that planetary melt analogues provide rich insight into important processes relevant to hot exoplanets and Earth's early history.
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Affiliation(s)
- O L G Alderman
- Materials Development, Inc., Arlington Heights, IL 60004, United States of America
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McCormack SJ, Tamalonis A, Weber RJK, Kriven WM. Temperature gradients for thermophysical and thermochemical property measurements to 3000 °C for an aerodynamically levitated spheroid. Rev Sci Instrum 2019; 90:015109. [PMID: 30709210 DOI: 10.1063/1.5055738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 12/04/2018] [Indexed: 06/09/2023]
Abstract
This study examines thermal gradients in ceramic oxide spheroids being aerodynamically levitated in a conical nozzle levitator (CNL) system equipped with a CO2 laser (10.6 µm wavelength). The CNL system is a versatile piece of equipment that can easily be coupled with advanced thermophysical and thermochemical measuring devices, such as diffraction/scattering (X-ray and neutron), nuclear magnetic resonance, and calorimetry, for the analysis of bulk spheroidal solids and liquids. The thermal gradients of a series of single crystal, polycrystalline solids, and liquid spheroids have been measured spatially in the CNL system, by means of a disappearing filament pyrometer (800-3000 °C) and by X-ray diffraction with reference to an internal standard (Pt: 800-1600 °C). The thermal gradient in a levitated sample being heated by a laser from the top can be minimized by: (i) maximizing the sphericity, (ii) maximizing the density, and (iii) minimizing microstructural features. A spheroid with these properties can be manufactured via machining a perfect sphere from a highly dense, chemically and phase pure pellet. These properties promote rotation of the sample about multiple axes in the air stream, enabling homogeneous heating. This homogeneous heating is the dominant factor in reducing thermal gradients in solid state samples. It was found that the thermal gradient in an ∼3 mm diameter solid sample could be reduced from 1000 °C to 30 °C, by having a perfectly spherical shape that could rotate on multiple axes in a high velocity gas stream (∼1500-2000 cm3/min). These findings will allow accurate thermophysical and thermochemical property measurements of solids in situ at high temperatures, using the CNL system.
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Affiliation(s)
- Scott J McCormack
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | | | - Waltraud M Kriven
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Calder S, An K, Boehler R, Dela Cruz CR, Frontzek MD, Guthrie M, Haberl B, Huq A, Kimber SAJ, Liu J, Molaison JJ, Neuefeind J, Page K, Dos Santos AM, Taddei KM, Tulk C, Tucker MG. A suite-level review of the neutron powder diffraction instruments at Oak Ridge National Laboratory. Rev Sci Instrum 2018; 89:092701. [PMID: 30278771 DOI: 10.1063/1.5033906] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/19/2018] [Indexed: 06/08/2023]
Abstract
The suite of neutron powder diffractometers at Oak Ridge National Laboratory (ORNL) utilizes the distinct characteristics of the Spallation Neutron Source and High Flux Isotope Reactor to enable the measurements of powder samples over an unparalleled regime at a single laboratory. Full refinements over large Q ranges, total scattering methods, fast measurements under changing conditions, and a wide array of sample environments are available. This article provides a brief overview of each powder instrument at ORNL and details the complementarity across the suite. Future directions for the powder suite, including upgrades and new instruments, are also discussed.
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Affiliation(s)
- S Calder
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - K An
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - R Boehler
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - C R Dela Cruz
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - M D Frontzek
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - M Guthrie
- European Spallation Source, Lund 221 00, Sweden
| | - B Haberl
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - A Huq
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - S A J Kimber
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - J Liu
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - J J Molaison
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - J Neuefeind
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - K Page
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - A M Dos Santos
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - K M Taddei
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - C Tulk
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
| | - M G Tucker
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, Tennessee 37831, USA
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Strand J, Kaviani M, Gao D, El-Sayed AM, Afanas'ev VV, Shluger AL. Intrinsic charge trapping in amorphous oxide films: status and challenges. J Phys Condens Matter 2018; 30:233001. [PMID: 29692368 DOI: 10.1088/1361-648x/aac005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We review the current understanding of intrinsic electron and hole trapping in insulating amorphous oxide films on semiconductor and metal substrates. The experimental and theoretical evidences are provided for the existence of intrinsic deep electron and hole trap states stemming from the disorder of amorphous metal oxide networks. We start from presenting the results for amorphous (a) HfO2, chosen due to the availability of highest purity amorphous films, which is vital for studying their intrinsic electronic properties. Exhaustive photo-depopulation spectroscopy measurements and theoretical calculations using density functional theory shed light on the atomic nature of electronic gap states responsible for deep electron trapping observed in a-HfO2. We review theoretical methods used for creating models of amorphous structures and electronic structure calculations of amorphous oxides and outline some of the challenges in modeling defects in amorphous materials. We then discuss theoretical models of electron polarons and bi-polarons in a-HfO2 and demonstrate that these intrinsic states originate from low-coordinated ions and elongated metal-oxygen bonds in the amorphous oxide network. Similarly, holes can be captured at under-coordinated O sites. We then discuss electron and hole trapping in other amorphous oxides, such as a-SiO2, a-Al2O3, a-TiO2. We propose that the presence of low-coordinated ions in amorphous oxides with electron states of significant p and d character near the conduction band minimum can lead to electron trapping and that deep hole trapping should be common to all amorphous oxides. Finally, we demonstrate that bi-electron trapping in a-HfO2 and a-SiO2 weakens Hf(Si)-O bonds and significantly reduces barriers for forming Frenkel defects, neutral O vacancies and O2- ions in these materials. These results should be useful for better understanding of electronic properties and structural evolution of thin amorphous films under carrier injection conditions.
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Affiliation(s)
- Jack Strand
- Department of Physics, University College London, Gower Street, London WC1E 6BT, United Kingdom
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10
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Olds D, Saunders CN, Peters M, Proffen T, Neuefeind J, Page K. Precise implications for real-space pair distribution function modeling of effects intrinsic to modern time-of-flight neutron diffractometers. Acta Crystallogr A Found Adv 2018; 74:293-307. [DOI: 10.1107/s2053273318003224] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 02/23/2018] [Indexed: 11/10/2022]
Abstract
Total scattering and pair distribution function (PDF) methods allow for detailed study of local atomic order and disorder, including materials for which Rietveld refinements are not traditionally possible (amorphous materials, liquids, glasses and nanoparticles). With the advent of modern neutron time-of-flight (TOF) instrumentation, total scattering studies are capable of producing PDFs with ranges upwards of 100–200 Å, covering the correlation length scales of interest for many materials under study. Despite this, the refinement and subsequent analysis of data are often limited by confounding factors that are not rigorously accounted for in conventional analysis programs. While many of these artifacts are known and recognized by experts in the field, their effects and any associated mitigation strategies largely exist as passed-down `tribal' knowledge in the community, and have not been concisely demonstrated and compared in a unified presentation. This article aims to explicitly demonstrate, through reviews of previous literature, simulated analysis and real-world case studies, the effects of resolution, binning, bounds, peak shape, peak asymmetry, inconsistent conversion of TOF to d spacing and merging of multiple banks in neutron TOF data as they directly relate to real-space PDF analysis. Suggestions for best practice in analysis of data from modern neutron TOF total scattering instruments when using conventional analysis programs are made, as well as recommendations for improved analysis methods and future instrument design.
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Kohara S, Ohara K, Ishikawa T, Tamaru H, Weber R. Investigation of Structure and Dynamics in Disordered Materials Using Containerless Techniques with In-Situ Quantum Beam and Thermophysical Property Measurements. QuBS 2018; 2:5. [DOI: 10.3390/qubs2010005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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Alderman OLG, Benmore CJ, Weber JKR, Skinner LB, Tamalonis AJ, Sendelbach S, Hebden A, Williamson MA. Corium lavas: structure and properties of molten UO 2-ZrO 2 under meltdown conditions. Sci Rep 2018; 8:2434. [PMID: 29402944 DOI: 10.1038/s41598-018-20817-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/22/2018] [Indexed: 11/23/2022] Open
Abstract
In the exceedingly rare event of nuclear reactor core meltdown, uranium dioxide fuel reacts with Zircaloy cladding to produce eutectic melts which can subsequently be oxidized by coolant/moderator water. Oxidized corium liquids in the xUO2·(100 − x)ZrO2 system were produced via laser melting of UO2-ZrO2 mixtures to temperatures in excess of 3000 K. Contamination was avoided by floating the droplets on a gas stream within an aerodynamic levitator and in-situ high-energy x-ray diffraction experiments allowed structural details to be elucidated. Molecular dynamics simulations well reproduced diffraction and density data, and show less compositional variation in thermal expansion and viscosity than suggested by existing measurements. As such, corium liquids maintain their highly penetrating nature irrespective of the amount of oxidized cladding dissolved in the molten fuel. Metal-oxygen coordination numbers vary with both composition and temperature. The former is due to mismatch in native values, nUO(x = 100) ≈ 7 and nZrO(x = 0) ≈ 6, and the requirement for oxygen site stabilization. The latter provides a thermal expansion mechanism.
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Abstract
Although anomalous melt properties have been attributed to the presence of triply coordinated oxygen ([3]O), the presence of [3]O in covalent amorphous oxides has not been revealed experimentally; such verification is the Holy Grail in the study of the physics and chemistry of glasses. We report the first 17O NMR spectrum for amorphous Al2O3 and reveal the hidden nature of [3]O. The detailed NMR characteristics of the oxygen tricluster are distinct from those estimated for the crystalline analogs, thus indicating its unique structure. This unambiguous evidence of the presence of [3]O allows us to microscopically constrain its glass-forming ability and unique two-step crystallization paths of amorphous Al2O3 through the annihilation of glassy [3]O with multiple [5]Al species.
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Affiliation(s)
- Sung Keun Lee
- Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University , Seoul 151-742, Korea
- Institute of Applied Physics, Seoul National University , Seoul 151-742, Korea
| | - Saebom Ryu
- Laboratory of Physics and Chemistry of Earth Materials, School of Earth and Environmental Sciences, Seoul National University , Seoul 151-742, Korea
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Gallington LC, Ghadar Y, Skinner LB, Weber JKR, Ushakov SV, Navrotsky A, Vazquez-Mayagoitia A, Neuefeind JC, Stan M, Low JJ, Benmore CJ. The Structure of Liquid and Amorphous Hafnia. Materials (Basel) 2017; 10:E1290. [PMID: 29125579 DOI: 10.3390/ma10111290] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 11/01/2017] [Accepted: 11/02/2017] [Indexed: 11/25/2022]
Abstract
Understanding the atomic structure of amorphous solids is important in predicting and tuning their macroscopic behavior. Here, we use a combination of high-energy X-ray diffraction, neutron diffraction, and molecular dynamics simulations to benchmark the atomic interactions in the high temperature stable liquid and low-density amorphous solid states of hafnia. The diffraction results reveal an average Hf–O coordination number of ~7 exists in both the liquid and amorphous nanoparticle forms studied. The measured pair distribution functions are compared to those generated from several simulation models in the literature. We have also performed ab initio and classical molecular dynamics simulations that show density has a strong effect on the polyhedral connectivity. The liquid shows a broad distribution of Hf–Hf interactions, while the formation of low-density amorphous nanoclusters can reproduce the sharp split peak in the Hf–Hf partial pair distribution function observed in experiment. The agglomeration of amorphous nanoparticles condensed from the gas phase is associated with the formation of both edge-sharing and corner-sharing HfO6,7 polyhedra resembling that observed in the monoclinic phase.
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15
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Wu YH, Wang WL, Yan N, Wei B. Experimental investigations and phase-field simulations of triple-phase-separation kinetics within liquid ternary Co-Cu-Pb immiscible alloys. Phys Rev E 2017; 95:052111. [PMID: 28618464 DOI: 10.1103/physreve.95.052111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Indexed: 11/07/2022]
Abstract
The phase-separation kinetics and microstructure evolution mechanisms of liquid ternary Co_{43}Cu_{40}Pb_{17} immiscible alloys are investigated by both the drop tube technique and phase-field method. Two successive phase separations take place during droplet falling and lead to the formation of a three-phase three-layer core-shell structure composed of a Co-rich core, a Cu-rich middle layer, and a Pb-rich shell. The Pb-rich shell becomes more and more conspicuous as droplet diameter decreases. Meanwhile, the Co-rich core center gradually moves away from the core-shell center. Theoretical analyses show that a larger temperature gradient inside a smaller alloy droplet induces the accelerated growth of the surface segregation shell during triple-phase separation. The residual Stokes motion and the asymmetric Marangoni convection result in the appearance of an eccentric Co-rich core and the core deviation degree is closely related to the droplet size and initial velocity. A three-dimensional phase-field model of ternary immiscible alloys, which considers the successive phase separations under the combined effects of Marangoni convection and surface segregation, is proposed to explore the formation mechanisms of three-phase core-shell structures. The simulated core-shell morphologies are consistent with the experimental observations, which verifies the model's validity in reproducing the core-shell dynamic evolution. Numerical results reveal that the development of three-phase three-layer core-shell structures can be attributed to the primary and then secondary phase separations dominated simultaneously by Marangoni convection and surface segregation. Furthermore, the effects of droplet temperature gradient on the growth kinetics of the surface segregation shell are analyzed in the light of phase-field theory.
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Affiliation(s)
- Y H Wu
- Department of Applied and Physics, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - W L Wang
- Department of Applied and Physics, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - N Yan
- Department of Applied and Physics, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - B Wei
- Department of Applied and Physics, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
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Wilding MC, Wilson M, Ribeiro MCC, Benmore CJ, Weber JKR, Alderman OLG, Tamalonis A, Parise JB. The structure of liquid alkali nitrates and nitrites. Phys Chem Chem Phys 2017; 19:21625-21638. [PMID: 28766680 DOI: 10.1039/c7cp03465b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
State of the art high energy X-ray diffraction experiments and simulation models (employing a description of charge transfer) are applied to pure molten alkali nitrates and nitrites and uncover significant emerging structure.
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Affiliation(s)
| | - Mark Wilson
- Department of Chemistry
- Physical and Theoretical Chemistry Laboratory
- University of Oxford
- Oxford OX1 3QZ
- UK
| | - Mauro C. C. Ribeiro
- Laboratório de Espectroscopia Molecular
- Instituto de Química
- Universidade de Sāo Paulo
- Sāo Paulo
- Brazil
| | | | - J. K. R. Weber
- X-ray Science Division
- Argonne National Laboratory
- Argonne
- USA
- Materials Development Inc
| | - O. L. G. Alderman
- X-ray Science Division
- Argonne National Laboratory
- Argonne
- USA
- Materials Development Inc
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17
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Liu M, Jacob A, Schmetterer C, Masset PJ, Hennet L, Fischer HE, Kozaily J, Jahn S, Gray-Weale A. From atomic structure to excess entropy: a neutron diffraction and density functional theory study of CaO-Al₂O₃-SiO₂ melts. J Phys Condens Matter 2016; 28:135102. [PMID: 26940854 DOI: 10.1088/0953-8984/28/13/135102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Calcium aluminosilicate CaO-Al2O3-SiO2 (CAS) melts with compositions (CaO-SiO2)(x)(Al2O3)(1-x) for x < 0.5 and (Al2O3)(x)(SiO2)(1-x) for x ≥ 0.5 are studied using neutron diffraction with aerodynamic levitation and density functional theory molecular dynamics modelling. Simulated structure factors are found to be in good agreement with experimental structure factors. Local atomic structures from simulations reveal the role of calcium cations as a network modifier, and aluminium cations as a non-tetrahedral network former. Distributions of tetrahedral order show that an increasing concentration of the network former Al increases entropy, while an increasing concentration of the network modifier Ca decreases entropy. This trend is opposite to the conventional understanding that increasing amounts of network former should increase order in the network liquid, and so decrease entropy. The two-body correlation entropy S2 is found to not correlate with the excess entropy values obtained from thermochemical databases, while entropies including higher-order correlations such as tetrahedral order, O-M-O or M-O-M bond angles and Q(N) environments show a clear linear correlation between computed entropy and database excess entropy. The possible relationship between atomic structures and excess entropy is discussed.
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Affiliation(s)
- Maoyuan Liu
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
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18
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Benmore CJ, Skinner LB, Lee B, Weber JKR, Parise JB, Williamson M. Topological ordering in liquid UO2. J Phys Condens Matter 2016; 28:015102. [PMID: 26656592 DOI: 10.1088/0953-8984/28/1/015102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A molecular dynamics model of liquid UO2 that is in good agreement with recent high-energy x-ray diffraction data has been analyzed using the Bhatia-Thornton formalism. A pre-peak appears in the topological structure factor S NN(Q) at Q = 1.85(1)Å(-1) which is not present in the more common, element specific Faber-Ziman partial structure factors. A radical Voronoi tessellation of the 3D molecular dynamics model shows the presence of a wide distribution of clusters, consistent with presence of highly mobile oxygen atoms. However, 4-fold Voronoi polyhedra (n 4) are found to dominate the structure and the majority of clusters can be described by the distribution n 3 ⩽ n 4 ⩾ n 5. It is argued that an open network of 4-fold Voronoi polyhedra could explain the origin of the pre-peak in S NN(Q) and the topological ordering observed in liquid UO2.
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Affiliation(s)
- C J Benmore
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
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19
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Abstract
Core (3 nm diameter) and outer surface layer (0.5 nm width) of a CuO nanoparticle of 4 nm in diameter.
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Affiliation(s)
- Alauddin Ahmed
- Department of Mechanical Engineering
- Chemical Engineering
- University of Michigan
- Ann Arbor
- USA
| | - Paolo Elvati
- Department of Mechanical Engineering
- Chemical Engineering
- University of Michigan
- Ann Arbor
- USA
| | - Angela Violi
- Department of Mechanical Engineering
- Chemical Engineering
- University of Michigan
- Ann Arbor
- USA
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20
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Kohara S, Akola J, Patrikeev L, Ropo M, Ohara K, Itou M, Fujiwara A, Yahiro J, Okada JT, Ishikawa T, Mizuno A, Masuno A, Watanabe Y, Usuki T. Atomic and electronic structures of an extremely fragile liquid. Nat Commun 2014; 5:5892. [PMID: 25520236 PMCID: PMC4284809 DOI: 10.1038/ncomms6892] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 11/18/2014] [Indexed: 01/22/2023] Open
Abstract
The structure of high-temperature liquids is an important topic for understanding the fragility of liquids. Here we report the structure of a high-temperature non-glass-forming oxide liquid, ZrO2, at an atomistic and electronic level. The Bhatia-Thornton number-number structure factor of ZrO2 does not show a first sharp diffraction peak. The atomic structure comprises ZrO5, ZrO6 and ZrO7 polyhedra with a significant contribution of edge sharing of oxygen in addition to corner sharing. The variety of large oxygen coordination and polyhedral connections with short Zr-O bond lifetimes, induced by the relatively large ionic radius of zirconium, disturbs the evolution of intermediate-range ordering, which leads to a reduced electronic band gap and increased delocalization in the ionic Zr-O bonding. The details of the chemical bonding explain the extremely low viscosity of the liquid and the absence of a first sharp diffraction peak, and indicate that liquid ZrO2 is an extremely fragile liquid.
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Affiliation(s)
- Shinji Kohara
- 1] Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo 679-5198, Japan [2] Schools of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1291, Japan
| | - Jaakko Akola
- 1] Department of Physics, Tampere University of Technology, PO Box 692, FI-33101 Tampere, Finland [2] COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland [3] Peter-Grünberg-Institut PGI-1, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Leonid Patrikeev
- 1] Department of Physics, Tampere University of Technology, PO Box 692, FI-33101 Tampere, Finland [2] Department of Mathematics and Physics, Faculty of Technology, Lappeenranta University of Technology, PO Box 20, FI-53851 Lappeenranta, Finland
| | - Matti Ropo
- 1] Department of Physics, Tampere University of Technology, PO Box 692, FI-33101 Tampere, Finland [2] COMP Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
| | - Koji Ohara
- Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo 679-5198, Japan
| | - Masayoshi Itou
- Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo 679-5198, Japan
| | - Akihiko Fujiwara
- 1] Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo 679-5198, Japan [2] Schools of Materials Science, Japan Advanced Institute of Science and Technology, Nomi, Ishikawa 923-1291, Japan
| | - Jumpei Yahiro
- 1] Research and Utilization Division, Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo, Hyogo 679-5198, Japan [2] Department of Condensed Matter Chemistry and Physics, Graduated School of Sciences, Kyushu University, Fukuoka 812-8581, Japan
| | - Junpei T Okada
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505, Japan
| | - Takehiko Ishikawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505, Japan
| | - Akitoshi Mizuno
- Department of Physics, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
| | - Atsunobu Masuno
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan
| | - Yasuhiro Watanabe
- Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan
| | - Takeshi Usuki
- Graduate School of Science and Engineering, Yamagata University, Yamagata 990-8560, Japan
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21
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Skinner LB, Benmore CJ, Weber JKR, Williamson MA, Tamalonis A, Hebden A, Wiencek T, Alderman OLG, Guthrie M, Leibowitz L, Parise JB. Molten uranium dioxide structure and dynamics. Science 2014; 346:984-7. [PMID: 25414311 DOI: 10.1126/science.1259709] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.
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Affiliation(s)
- L B Skinner
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA. Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794-2100, USA. Materials Development, Inc., 3090 Daniels Court, Arlington Heights, IL 60004, USA.
| | - C J Benmore
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - J K R Weber
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA. Materials Development, Inc., 3090 Daniels Court, Arlington Heights, IL 60004, USA
| | - M A Williamson
- Chemical Science and Engineering, Argonne National Laboratory, Argonne, IL 60439, USA
| | - A Tamalonis
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | - A Hebden
- Chemical Science and Engineering, Argonne National Laboratory, Argonne, IL 60439, USA
| | - T Wiencek
- Nuclear Engineering, Argonne National Laboratory, Argonne, IL 60439, USA
| | - O L G Alderman
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA. Materials Development, Inc., 3090 Daniels Court, Arlington Heights, IL 60004, USA
| | - M Guthrie
- Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - L Leibowitz
- Chemical Science and Engineering, Argonne National Laboratory, Argonne, IL 60439, USA
| | - J B Parise
- Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794-2100, USA. Photon Sciences, Brookhaven National Laboratory, Upton, NY 11973, USA
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