Neutron Applications in Earth, Energyand Environmental Sciences

Neutron Scattering Applications and Techniques

Series Editors:Ian S. AndersonNeutron Sciences DirectorateOak Ridge National LaboratoryBuilding 8600, MS 6477Oak Ridge, TN 37831USAandersonian@ornl.gov

Alan J. HurdLujan Neutron Scattering Center at LANSCELos Alamos National LaboratoryPO Box 1663, MS H805Los Alamos, NM 87545USAajhurd@lanl.gov

Robert L. McGreevyISISScience & Technology Facilities CouncilRutherford Appleton LaboratoryHarwell Science & Innovation CampusChilton, Didcot OX11 0 QXUKrobert.mcgreevy@stfc.ac.uk

Neutron Applications in Earth, Energy, and Environmental SciencesLiyuan Liang, Romano Rinaldi, and Helmut Schober, eds.ISBN 978-0-387-09415-1, 2009

Liyuan Liang · Romano Rinaldi ·Helmut SchoberEditors

Neutron Applicationsin Earth, Energyand Environmental Sciences

123

EditorsLiyuan LiangOak Ridge National LaboratoryOak Ridge, TNUSAliangl@ornl.gov

Romano RinaldiUniversita di PerugiaItalyrrinaldi@unipg.it

Helmut SchoberInstitut Laue-LangevinGrenobleFranceschober@ill.fr

ISBN 978-0-387-09415-1 e-ISBN 978-0-387-09416-8DOI 10.1007/978-0-387-09416-8

Library of Congress Control Number: 2008932522

c© Springer Science+Business Media, LLC 2009All rights reserved. This work may not be translated or copied in whole or in part without the writtenpermission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York,NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use inconnection with any form of information storage and retrieval, electronic adaptation, computer software,or by similar or dissimilar methodology now known or hereafter developed is forbidden.The use in this publication of trade names, trademarks, service marks, and similar terms, even if they arenot identified as such, is not to be taken as an expression of opinion as to whether or not they are subject toproprietary rights.

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Preface

The use of neutrons to investigate the fundamental properties of materials beganwith the search for new ways of exploiting the knowledge and instrumentationacquired during the all-out scientific efforts of the Manhattan Project in the 1940s.Neutron applications were explored in the 1950s by Bertram N. Brockhouse at theChalk River Laboratory in Ontario and by Clifford G. Shull at the Graphite Reactorat Oak Ridge National Laboratory (ORNL) in Tennessee. When the Royal SwedishAcademy of Sciences awarded them the 1994 Nobel Prize in Physics, for pioneeringcontributions to the development of neutron scattering techniques, the citation notedthat they had between them helped to answer the questions of where atoms “are” andwhat atoms “do.” The saying “neutrons see where atoms are and what they do” hasbecome the motto of neutron scattering science.

Brockhouse’s and Shull’s pioneering applications were essentially limited tostudies of the physical properties of matter, and in particular to phase transitions,magnetic structures, phonons, and especially the hydrogen bond. In the last 20 yearsor so, the use of neutrons has expanded tremendously following the development ofnew technology for the production of cold, thermal, and epithermal neutrons. Thishas resulted in orders-of-magnitude improvements to brilliance, energy resolution,and detector efficiencies compared with the original sources and measuring devices.Many of the scientific applications that now employ neutrons were quite unantici-pated. Neutrons, with wavelengths on the order of angstroms, are capable of probingmolecular structures and motions and increasingly find applications in a wide arrayof scientific fields, including biochemistry, biology, biotechnology, cultural heritagematerials, earth and environmental sciences, engineering, material sciences, miner-alogy, molecular chemistry, and solid state and soft matter physics.

This volume surveys the diversity of present day applications of neutron methodsin the fields of Earth, Energy, and Environmental Sciences. Neutron applications inEarth sciences, including mineralogy, petrology, geochemistry, volcanology, struc-tural geology, and sedimentology, are presented first for structural studies. The sec-ond set of applications is in the area of energy, particularly the sources of energy,upon which our modern civilization depends. In view of the inevitable exhaustionof natural fossil fuels, energy alternatives are needed for sustainable advancement.The last aspect of the Earth system dealt with, the environment, of course, becomes

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prominent in any of the studies addressed under the other two denominations, forenergy use is linked to impacts to the natural environment of the planet Earth.

The book intends to provide the novice with an inspiring introduction to theuse of neutrons in material science and technology and to stimulate the expert toconsider these non-conventional techniques as readily available problem-solvingtools in the fields of application considered. The International Year of Planet Earth,as declared by the United Nations Educational, Scientific and Cultural Organiza-tion and the International Union of Geological Sciences for 2008, testifies to theincreased awareness of the strong ties linking these three fields.

The international scientific community has been engaged in a major effort toproduce the next generation of large-scale neutron sources and instruments, alongwith the newest synchrotron-based X-ray facilities, in response to an ever growingdemand for knowledge of the fundamental properties of materials (natural or man-made, organic or inorganic) and their scientific and technological implications.

The coming on-line of a new generation of spallation neutron sources, for exam-ple, at Oak Ridge National Laboratory (ORNL) (Fig. 1) in the United States andat Tsukuba, Japan (Fig. 2), represent the most tangible aspects of this effort. Addi-tionally, the construction of ISIS-TS2, the second target station at the spallationneutron source (ISIS) of the Rutherford Laboratory in the United Kingdom, is wellon its way to completion (Fig. 3); and construction is expected to begin soon forthe Chinese source (CSNS) in Dong-guan, People’s Republic of China. At the sametime, efforts have been completed to renew the reactor-based neutron sources forthe ORNL High-Flux Isotope Reactor and the research reactor at Grenoble, France(Fig. 4). The latter, supported by the Institut Laue-Langevin Millennium Programme(www.ill.fr), provided an order-of-magnitude gain at the experimental stations. TheEuropean Spallation Source has been planned for over 12 years, and constructionseems imminent. This project is to build and operate the world’s most intense

Fig. 1 Arial view of the pulsed Spallation Neutron Source at Oak Ridge National Laboratory,USA, completed and in operation in 2008. Photo courtesy of ORNL

Preface vii

Fig. 2 The new Japanese pulsed Spallation Neutron Source (JSNS) close to completion as a Mate-rials and Life Science Facility at J-PARC, Tsukuba, Japan. Photo courtesy of JAERI

Fig. 3 Aerial view of ISIS and TS2 (the box-shaped building in foreground right) at the RutherfordAppleton Laboratory, UK. Part of the new synchrotron ring Diamond is visible on the upper rightside. Photo courtesy of RAL

neutron source. It is currently one of the largest research and development infras-tructures slated to be built in Europe during the next 10 years, with an estimatedconstruction cost of 1.0–1.5 G€.

The editors—in the hope that these present day neutron applications in stud-ies of the Earth, energy, and the environment help stimulate novel uses of neu-trons to unveil otherwise unobtainable information—are grateful to all the con-tributors whose insights, diligence, and timeliness made this volume possible. Ourthanks also go to the ORNL and Springer editorial staff: D. Counce, V. J. Ewing,C. Horak, E. Tham, and L. Danahy, whose assistance is critical to this volume. Weare indebted to the following reviewers and the series editors (Ian Anderson, AlanHurd, and Robert McGreevy) whose suggestions helped us maintain balance andaccuracy: Alberto Albinati, Muhammad Arif, Miguel Angel Castro Arroyo, CraigBrown, Michele Catti, Jack Carpenter, Gabrial Cuello, Wulf Depmeier, A. N. Fitch,

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Fig. 4 Aerial view of the Institut Laue-Langevin reactor building, Grenoble, France. Part of theEuropean Synchrotron Radiation Facility ring is visible to the right of the reactor dome. PhotoCourtesy of ILL

Jean Louis Fourquet, Yoshiyuki Inaguma, A. Johs, Walter Kob, David Lennon,E. Lehmann, Li Liu, Chun Loong, Geoff Lloyd, Yuri Melnichenko, Laurent Michot,D. A. Neumann, Michael Prager, Werner Press, Alessandro Pavese, Keith Ross, PaulSchofield, Holger Stunitz, Jose Teixeira , Wolfgang Treimer, Costas Tsouris, SvenVogel, Peter Votonbel, Thomas Voigtmann, Hanna Wacklin, and Michele Zucali.

Special thanks go to our families: Robert, Mark, and Katherine; Jenny, Victoriaand Alexandra; Anita, Alexander, Rafaela and Carmen for their patience, support,and understanding during the many months of our involvement in this endeavour.

Oak Ridge, TN, USA Liyuan LiangPerugia, Italy Romano RinaldiGrenoble, France Helmut Schober

Contents

1 Neutron Applications in Earth, Energy, and Environmental Sciences 1Romano Rinaldi, Liyuan Liang, and Helmut Schober

2 Neutron Scattering—A Non-destructive Microscope for SeeingInside Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Roger Pynn

3 Neutron Scattering Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Helmut Schober

Part I Applications: Earth Sciences

4 Structural and Magnetic Phase Transitionsin Minerals: In Situ Studies by Neutron Scattering . . . . . . . . . . . . . . . . 107Simon A. T. Redfern and Richard J. Harrison

5 Inelastic Neutron Scattering and Lattice Dynamics: Perspectivesand Challenges in Mineral Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145Narayani Choudhury and Samrath Lal Chaplot

6 A Microscopic View of Mass Transport in Silicate Melts byQuasielastic Neutron Scattering and Molecular DynamicsSimulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189Andreas Meyer, Florian Kargl, and Jurgen Horbach

7 Neutron Diffraction Studies of Hydrous Minerals in Geosciences . . . . 211Hermann Gies

8 Studies of Mineral–Water Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235Nancy L. Ross, Elinor C. Spencer, Andrey A. Levchenko, AlexanderI. Kolesnikov, David J. Wesolowski, David R. Cole, EugeneMamontov, and Lukas Vlcek

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9 Neutron Diffraction and the Mechanical Behavior of GeologicalMaterials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257Stephen J. Covey-Crump and Paul F. Schofield

10 The Contribution of Neutron Texture Goniometry to the Study ofComplex Tectonics in the Alps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Jan Pleuger, Nikolaus Froitzheim, Jan F. Derks, Walter Kurz, JanAlbus, Jens M. Walter, and Ekkehard Jansen

11 Neutron Imaging Methods and Applications . . . . . . . . . . . . . . . . . . . . . . 319Eberhard H. Lehmann

Part II Applications: Energy

12 Vibrational Dynamics and Guest–Host Coupling in ClathrateHydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351Michael M. Koza and Helmut Schober

13 Applications of Neutron Scattering in the Chemical Industry:Proton Dynamics of Highly Dispersed Materials, Characterizationof Fuel Cell Catalysts, and Catalysts from Large-Scale ChemicalProcesses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391Peter W. Albers and Stewart F. Parker

14 Hydrogen and Hydrogen-Storage Materials . . . . . . . . . . . . . . . . . . . . . . 417Milva Celli, Daniele Colognesi, and Marco Zoppi

15 Lithium Ion Materials for Energy Applications: StructuralProperties from Neutron Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439Michele Catti

Part III Applications: Environment

16 Application of Neutron Reflectivity for Studies of BiomolecularStructures and Functions at Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . 463Alexander Johs, Liyuan Liang, Baohua Gu, John F. Ankner, and WeiWang

17 Pollutant Speciation in Water and Related EnvironmentalTreatment Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491Gabriel J. Cuello, Gabriela Roman-Ross, Alejandro Fernandez-Martınez, Oleg Sobolev, Laurent Charlet, and Neal T. Skipper

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18 Clay Swelling: New Insights from Neutron-Based Techniques . . . . . . . 521Isabelle Bihannic, Alfred Delville, Bruno Deme, Marie Plazanet,Frederic Villieras, and Laurent J. Michot

19 Structure and Dynamics of Fluids in Microporous and MesoporousEarth and Engineered Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 547David R. Cole, Eugene Mamontov, and Gernot Rother

20 The Combined Ultra-Small- and Small-Angle Neutron Scattering(USANS/SANS) Technique for Earth Sciences . . . . . . . . . . . . . . . . . . . . . 571Roberto Triolo and Michael Agamalian

21 Biosynthesis of Magnetite by Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . 595Sarah S. Staniland, Bruce Ward, and Andrew Harrison

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 619

Contributors

Michael Agamalian Neutron Scattering Science Division, Oak Ridge NationalLaboratory, MS-6475, Oak Ridge, TN 37831-6475, USAmagamalian@ornl.gov

Peter W. Albers AQura GmbH, AQ-EM, Rodenbacher Chaussee 4, D-63457Hanau, Germanypeter.albers@aqura.de

Jan Albus Geologisches Institut, Nussallee 8, D-53115 Bonn, GermanyJan.Albus@freenet.de

Ian Anderson Neutron Scattering Sciences Division, Oak Ridge NationalLaboratory, MS-6475, Oak Ridge, TN 37831-6475, USAandersonian@ornl.gov

John F. Ankner Neutron Scattering Science Division, Oak Ridge NationalLaboratory, MS 6475, 1 Bethel Valley Road, Oak Ridge, TN 37831-6475, USAanknerjf@ornl.gov

Isabelle Bihannic Laboratoire Environnement et Mineralurgie, UMR 7569CNRS-INPL-ENSG, 15, Av. du Charmois, BP 40, F-54501 Vandoeuvre Les NancyCedex, Franceisabelle.bihannic@ensg.inpl-nancy.fr

Michele Catti Dipartimento di Scienza dei Materiali, Universita di MilanoBicocca, Via Cozzi 53, I-20125 Milano, Italycatti@mater.unimib.it

Milva Celli CNR-Istituto Sistemi Complessi, Via della Madonna del Piano, 10,I-50019 Sesto Fiorentino, Italymilva.celli@isc.cnr.it

Daniele Colognesi CNR-Istituto Sistemi Complessi, Via della Madonna del Piano,10, I-50019 Sesto Fiorentino, Italydaniele.colognesi@isc.cnr.it

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Samrath Lal Chaplot Solid State Physics Division, Bhabha Atomic ResearchCentre, Mumbai 400085, Indiachaplot@magnum.barc.gov.in

Laurent Charlet Environmental Geochemistry Group, University of Grenoble-I,LGIT, B.P. 53, F-38041 Grenoble Cedex, Francelaurent.charlet@obs.ujf-grenoble.fr

Narayani Choudhury Solid State Physics Division, Bhabha Atomic ResearchCentre, Mumbai 400085, Indiadynamics@barc.gov.in; chaplot@barc.gov.com

David R. Cole Chemical Sciences Division, Oak Ridge National Laboratory,MS-6110, Oak Ridge, TN 37831-6110, USAcoledr@ornl.gov

Stephen J. Covey-Crump School of Earth, Atmospheric and EnvironmentalSciences, University of Manchester, Oxford Road, Manchester, M13 9PL, UKS.Covey-Crump@manchester.ac.uk

Gabriel J. Cuello Diffraction Group, Institut Laue Langevin, 6, Rue JulesHorowitz, B.P.156, F-38042 Grenoble Cedex 9, Francecuello@ill.fr

Alfred Delville Centre de Recherche sur la Matiere Divisee, CNRS-OrleansUniversity, 1b rue de la Ferollerie, F-45071 Orleans Cedex 2, Francedelville@cnrs-orleans.fr

Bruno Deme Institut Laue-Langevin, 6 rue Jules Horowitz, F-38042 GrenobleCedex 9, Francedeme@ill.fr

Jan F. Derks IES Integrated Exploration Systems, Ritterstr. 23, 52072 Aachen,Germanyj.derks@ies.de

Alejandro Fernandez-Martınez Institut Laue-Langevin, B.P. 156, F-38042Grenoble, Francefernande@ill.fr

Nikolaus Froitzheim Geologisches Institut, Nussallee 8, D-53115 Bonn, Germanyniko.froitzheim@uni-bonn.de

Hermann Gies Institut fur Geologie, Mineralogie and Geophysik, Ruhr-Universitat Bochum, Universitatsstr. 150, D-44780 Bochum, GermanyHermann.Gies@ruhr-uni-bochum.de

Baohua Gu Environmental Sciences Division, Oak Ridge National Laboratory,MS-6036, Oak Ridge, TN 37831-6036, USAgub1@ornl.gov

Contributors xv

Andrew Harrison Institut Laue Langevin (ILL), 6, Rue Jules Horowitz, B.P.156,F-38042 Grenoble Cedex 9, FranceHarrison@ill.fr

Richard J. Harrison Department of Earth Sciences, University of Cambridge,Downing Street, Cambridge, CB2 3EQ, UKrjh40@esc.cam.ac.uk

Jurgen Horbach Institut fur Materialphysik im Weltraum, Deutsches Zentrum furLuft- und Raumfahrt (DLR), D-51170 Koln, Germanyjuergen.horbach@dlr.de

Ekkehard Jansen Steinmann-Institut der Universitat Bonn, Abteilung EndogeneProzesse, Poppelsdorfer Schloß, D-53115 Bonn, Germanye.jansen@fz-juelich.de

Alexander Johs Environmental Sciences Division, Oak Ridge NationalLaboratory, MS-6038, Oak Ridge, TN 37831-6038, USAjohsa@ornl.gov

Florian Kargl Institute of Mathematics and Physics, Aberystwyth University,Aberystwyth SY23 3BZ, UKffk@aber.ac.uk

Alexander I. Kolesnikov Intense Pulsed Neutron Source Division, ArgonneNational Laboratory, Argonne IL 60439, USAakolesnikov@anl.gov

Michael M. Koza Institut Laue Langevin, 6 rue Jules Horowitz, B.P. 156, F-38042Grenoble Cedex 9, Francekoza@ill.fr

Walter Kurz Institute of Applied Geosciences, Graz University of Technology,Rechbauerstr. 12, A-8010, Graz, Austriawalter.kurz@tugraz.at

Eberhard H. Lehmann Spallation Neutron Source Division, Paul ScherrerInstitut, CH-5232 Villigen, Switzerlandeberhard.lehmann@psi.ch

Andrey A. Levchenko Peter A. Rock Thermochemistry Laboratory and NEATORU, University of California, Davis, CA 95616, USAalevchenko@ucdavid.edu

Liyuan Liang Environmental Sciences Division, Oak Ridge National Laboratory,MS-6038, Oak Ridge, TN 37831-6038, USAliangl@ornl.gov

Eugene Mamontov Neutron Scattering Science Division, Oak Ridge NationalLaboratory, MS-6475, Oak Ridge, TN 37831-6475, USAmamontove@ornl.gov

xvi Contributors

Andreas Meyer Institut fur Materialphysik im Weltraum, Deutsches Zentrum furLuft- und Raumfahrt (DLR), 51170 Koln, Germanyandreas.meyer@dlr.de

Laurent J. Michot Laboratoire Environnement et Mineralurgie, UMR 7569CNRS-INPL-ENSG, 15, Av. du Charmois, BP 40, F-54501 Vandoeuvre Les NancyCedex, FranceLaurent.michot@ensg.inpl-nancy.fr

Stewart F. Parker ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot,Oxfordshire, OX11 0QX, UKs.f.parker@rl.ac.uk

Marie Plazanet Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 GrenobleCedex 9, Franceplazanet@ill.fr

Jan Pleuger Geologisches Institut der ETH Zurich, CH-8092 Zurich, SwitzerlandJan.pleuger@erdw.ethz.ch

Roger Pynn Indiana University Cyclotron Facility, 2401 Milo B. Sampson Ln,Bloomington, IN 47408-1398, USArpynn@indiana.edu

Simon A. T. Redfern Earth Sciences, University of Cambridge, Cambridge, CB23EQ, UKsatr@esc.cam.ac.uk

Romano Rinaldi Dipartimento di Scienze della Terra, Universita’ di Perugia,I-06100 Perugia, Italyrrinaldi@unipg.it

Gabriela Roman-Ross Environmental Geochemistry Group, LGIT, UniversiteJoseph Fourier, F-38401, Francegabriela.Roman-Ross@obs.ujf-grenoble.fr

Nancy L. Ross Department of Geosciences, Crystallography Laboratory, VirginiaTech, Blacksburg, VA 24061, USAnross@vt.edu

Gernot Rother Chemical Sciences Division, Oak Ridge National Laboratory,MS-6110, Oak Ridge, TN 37831-6110, USArotherg@ornl.gov

Helmut Schober Time-of-Flight and High Resolution Group, Institut Laue-Langevin, 6, rue Jules Horowitz BP 156, F-38042 Grenoble Cedex 9, Franceschober@ill.fr

Paul F. Schofield Department of Mineralogy, Natural History Museum, CromwellRoad, London SW7 5BD, UKpfs@nhm.ac.uk

Contributors xvii

Neal T. Skipper Department of Physics and Astronomy, University CollegeLondon, Gower Street, London WC1E 6BT, UKn.skipper@ucl.ac.uk

Oleg Sobolev Laboratoire de Geophysique Interne et Tectonophysique 1381, ruede la Piscine, F-38041 Grenoble, Francesobolev@ill.eu

Elinor C. Spencer Department of Geosciences, Crystallography Laboratory,Virginia Tech, Blacksburg, VA 24061, USAespence@vt.edu

Sarah S. Staniland School of Biological Sciences, University of Edinburgh, TheKing’s Buildings, Edinburgh, EH9 3JR, UKs.staniland@ed.ac.uk

Roberto Triolo The University of Palermo, I-90128 Palermo, Italytriolo@unipa.it

Frederic Villieras Laboratoire Environnement et Mineralurgie, UMR 7569CNRS-INPL-ENSG, 15, Av. du Charmois, BP 40, F-54501 Vandoeuvre Les NancyCedex, Francefrederic.villieras@ensg.inpl-nancy.fr

Lukas Vlcek Department of Chemical Engineering, Vanderbilt University,Nashville, TN 37235, USAlukas.vlcek@Vanderbilt.Edu

Jens M. Walter Geowissenschaftliches Zentrum der Universitat Gottingen,Goldschmidtstraße 3, D-37077 Gottingen, Germanyjwalter@gwdg.de

Wei Wang Environmental Sciences Division, Oak Ridge National Laboratory,MS-6036, Oak Ridge, TN 37831-6036, USAwnagw@ornl.gov

Bruce Ward School of Chemistry and EaStChem, The University of Edinburgh,The King’s Buildings, Edinburgh, EH9 3JJ, UKb.ward@ed.ac.uk

David J. Wesolowski Chemical Sciences Division, Oak Ridge NationalLaboratory, MS-6110, Oak Ridge, TN 37831-6110, USAwesolowskid@ornl.gov

Marco Zoppi Consiglio Nazionale delle Ricerche (CNR)-Istituto SistemiComplessi, Via della Madonna del Piano, 10, I-50019 Sesto Fiorentino, Italymarco.zoppi@isc.cnr.it

Chapter 1Neutron Applications in Earth, Energy,and Environmental Sciences

Romano Rinaldi, Liyuan Liang, and Helmut Schober

Abstract Neutron-based studies permit the determination of the structural detailsand the dynamics of atomic arrangements in materials from simple measurementsof scattering and absorption processes. Neutrons are scattered by atomic nuclei,are sensitive to the atomic magnetic moment, and have scattering and absorptioncross-sections independent of atomic number and mass. They therefore have a com-plementary role to X-rays, scattered by the electrons in atoms. A prominent aspectof this lies in the sensitivity of neutrons to light elements, in particular hydrogen,a ubiquitous component of organic and inorganic matter and a key component ofEarth, energy, and environment-related materials. Furthermore, thanks to the lowabsorption of neutrons by most substances, neutron scattering allows good qualitydata to be obtained over a wide range of non-ambient environments. This permitsstudies of transformations and fundamental properties of materials in situ, whilethey are still subject to the physical–chemical conditions in the diverse environmentsin which they normally exist and function, from the Earth’s surface to its deep inte-rior, and to laboratory conditions of one’s choice. The limitations traditionally con-nected with modest neutron flux, and consequent need for relatively large samples,are being overcome by current advances in neutron sources and instrumentation.As a result, the potential of neutron-based methods in the examination of materialsin Earth, energy, and environmental studies has gained momentum and opened updiverse new possibilities in these fields of scientific and technological research.

1.1 Introduction

The intrinsic properties of neutrons, as discussed in Chapter 2, make them a versatileprobe for the study of materials encountered in Earth, energy, and environmental sci-ences. Applications of neutrons in the Earth Sciences are relatively recent, but theprospect is promising because neutrons provide a unique, non-destructive methodof obtaining information ranging from the angstrom-scale of atomic structures and

R. Rinaldi (B)Dipartimento di Scienze della Terra, Universita’ di Perugia, I-06100 Perugia, Italye-mail: rrinaldi@unipg.it

L. Liang et al. (eds.), Neutron Applications in Earth, Energy and EnvironmentalSciences, Neutron Scattering Applications and Techniques,DOI 10.1007/978-0-387-09416-8 1, C© Springer Science+Business Media, LLC 2009

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related motions to the micron-scale of material strain, stress, and texture, as well asto the meso-scale of porous media and defects in materials and functional compo-nents. A full understanding of basic phenomena such as crustal subduction, earth-quakes, and volcanic eruptions depends on the physical, chemical, and rheologicalproperties of the materials involved (crustal and mantle rocks, magmas and fluids).These in turn depend on the structure and properties of the constituent mineralsand the associated hydrous components, which can be determined using neutrontechniques as described in this volume.

Similarly, materials involved in the technological developments required in thesearch for energy alternatives, and the fundamental processes involved in the seques-tration and transformation of toxic wastes to minimize environmental impact, canalso be profitably investigated by methods based on neutron sources. The modernworld is primarily dependent on energy from fossil fuels and mineral resources orig-inating from geological processes and materials within sediments and crustal rocks.The environment of living organisms is in turn threatened by the wastes generatedas well as by the rapid consumption of these energy reserves. This volume intends toprovide a representative number of examples of neutron applications bridging thesemany aspects of research related with the system Earth.

1.2 Neutron-Matter Interactions: Intrinsic Properties,Advantages, Disadvantages, and Complementarity

Of the many properties of neutrons (Chapter 2) as probes for the study of materials,the following are particularly relevant here:

• Neutrons have no electric charge.• They interact with the nuclei rather than with the charge distribution of atoms in

matter.• They have wavelengths in the range of interatomic distances. They have magnetic

moment and interact with the magnetic moment of atoms in matter.• Their mass (∼1 a.m.u.) is similar to that of atomic nuclei (1–240 a.m.u.), hence

they have energy and momentum similar to those of atoms in solid and fluidmaterials.

From these properties, a number of features emerge when considering the use ofneutrons in scattering and absorption experiments [1].

• Neutron scattering results from interactions with atomic nuclei, i.e., over scatter-ing lengths (distances) of the order of 10−15 m (1 fm). By comparison, X-rayinteractions (with electrons) occur over distances of 10−10 m (1 A), i.e., fiveorders of magnitude larger. Furthermore, scattering and absorption cross-sectionsof neutrons do not dependent in a systematic way upon atomic number and mass,allowing discrimination between neighbors and isotopes in the periodic table(Chapter 2).

1 Neutron Applications in Earth, Energy, and Environmental Sciences 3

• Although scattering amplitude decays greatly with the scattering vector Q (theinverse of the scattering length) for X-rays, there are insignificant variationsof scattering amplitude in the same range of Q (Bragg angle) for neutrons [2].Consequently, powder diffraction with neutrons can resolve very fine struc-tural and textural details of complex atomic structures, having access to a largenumber of reflections all the way to very short d spacings (very high Braggangles).

• The weak interaction of neutrons with matter results in very low attenuation (seeFig. 2.1 in Chapter 2) offering a unique advantage for non-destructive, in situwork and bulk analyses (with high grain statistics on large objects) of undisturbedsamples. For polycrystalline materials, no crushing is required to obtain powderpatterns.

• Resonance absorption of neutrons yields several useful applications, from themeasurement of temperature through the Doppler broadening of resonance lines[See Chapter 4, and Ref. 3] to the detection of trace element components of mate-rials by neutron resonance capture analysis [4].

• Direct imaging techniques, based on selective absorption of neutrons by differentatomic species and materials, also profit from the high penetration and offer arange of novel applications for bulk materials and apparatus, in energy, environ-mental, and plant sciences, etc., although still with less than optimum resolution.Lehmann et al. (Chapter 11) review such applications and the state of the art.

Fig. 1.1 The range of neutron diffraction compared with other experimental techniques. Whilethere is considerable overlap in terms of the length scale, the information obtained is often com-plementary due to different element specificity. Furthermore, magnetic structure determination isnearly entirely a domain of neutron scattering. Techniques in the lower half of the diagram aretypically only applied to very small samples [12]

4 R. Rinaldi et al.

Descriptions of the formalisms for neutron scattering (coherent and incoherent,elastic, magnetic and inelastic), and the principles of their application in neutroninstruments are found in [5] and in Chapters 2, 3, and 4 of this volume.

1.2.1 Advantages

A neutron probe offers the following advantages over more traditional methods ofmaterial analysis:

• The nuclear and non-linear dependence of neutron scattering for different atomicspecies readily permits discrimination between iso- or quasi-iso-electronic species.Neutrons have no fundamental limitations in probing light elements and in dis-tinguishing between isotopes.

• Neutron powder diffraction produces information beyond the range of X-raydiffraction and complementary to X-ray diffraction. The high penetration capa-bility of neutrons allows in situ analysis of samples by environmental equipment,such as high-temperature furnaces, low-temperature cryostats, high-pressure reac-tion cells, and differential loading frames, etc. Diffraction information is obtainedfrom the bulk of the sample rather than from the surface only. This is also relevantin the study of displacive phase transitions where surface behavior can be differ-ent from the bulk. The few very strong absorbers (e.g., B, Cd, Gd) can effectivelybe used for screening devices.

• A large neutron beam allows good sampling of the object under investigation,i.e., the data collected can be considered to be representative of the whole object.

• Systematic effects, such as absorption and preferred orientation, play an insignif-icant role in neutron diffraction analysis.

• Neutrons are produced via moderation in a thermal bath. They thus have by defi-nition energies similar to the energies of excitations in solids and liquids at thosemoderator temperatures. This makes neutrons unique tools for investigations ofenergies in the range of nano-eV to several eV, corresponding to time scales rang-ing from attoseconds to microseconds. This unique capacity combined with allthe other advantages already outlined above makes neutrons in many cases theonly probe capable of accessing dynamic processes, with a space resolution atthe atomic scale.

Other advantages are offered by time-of-flight (TOF) neutron diffraction atpulsed spallation sources (see Chapter 3). In the TOF mode, from a combina-tion of De Broglie’s relation (λ = h/mv , see Chapter 2) with Bragg’s law (λ =2dhkl sin θ ), one obtains the following TOF relation:

t(� sec) = 252.78 L(m)2dhkl (A) sin θ,

where L represents the flight path (in meters). The d spacing of the diffracting crystalplane (hkl) is thus resolved in time. The method is essentially wavelength dispersive

1 Neutron Applications in Earth, Energy, and Environmental Sciences 5

(time), with position-sensitive detectors having a time resolution of the order of 1 �sand a spatial resolution of the order of 1 mm. The advantages are therefore:

• A complete diffraction pattern is collected at any given scattering angle and over alarge range of angles from forward- to back-scattering directions. Measurementis made with a stationary experimental setup, i.e., neither sample nor detectormovements are required.

• Complete objects of variable shapes and sizes (even fairly large ones) can beinvestigated without prior preparation, by simple “immersion” in the neutronbeam. Some rotation may only be needed if the detectors do not cover a varietyof azimuth angles.

• TOF diffractometers provide optimum resolution in backscattering mode wherethe line width of diffraction peaks is largely independent of sample thickness;allowing line-width analyses to be performed for stress/strain measurements [6].

• Several banks of position-sensitive detectors used in TOF diffractometers covera large d-spacing range, permitting accurate determination of scale factors, i.e.,phase fractions in Rietveld analysis [7, 8] A multitude of detector elements pro-vides remarkably robust TOF neutron diffraction Rietveld refinements for theanalysis of fine structural details.

• Preferred orientation or texture effects are easily recognized, and the textural andmicrostructural information may even be an important part of the characterizationof the object [9].

Furthermore, the high peak intensity of a modern pulsed spallation source opensthe way to time-resolved kinetic measurements and pulse-probe techniques allowingmaterials to be investigated in non-equilibrium, or transient, conditions.

1.2.2 Disadvantages

Most disadvantages stem from the intrinsic relative limitations of neutron flux avail-able at conventional reactor sources, or at first-generation spallation sources. Thebrilliance of modern neutron sources is approximately 14 orders of magnitude lowerthan that of a third-generation synchrotron source. High-flux research reactors suchas the Institut Laue-Langevin (ILL, Grenoble, France) and the High-Flux IsotopeReactor (HFIR, Oak Ridge, TN) are currently operating close to the practical limitof brilliance for research reactor sources. Further increments can only be expectedfrom newer pulsed spallation sources [10]. The relatively low flux available atpresent at operating neutron beam lines obligates the use of relatively large samples(see Chapter 5 for examples of inelastic neutron scattering applications to singlecrystals) and very efficient detectors. This is being partly overcome in the mostrecent generation of pulsed neutron sources, such as the Spallation Neutron Sourceat Oak Ridge, USA [11], where high-brilliance neutron beams, large detector arrays,and TOF techniques have been implemented to great advantage.

6 R. Rinaldi et al.

1.2.3 Complementarity with Other Material Analysis Techniques

Neutron methods complement many other techniques to probe the intrinsic prop-erties of materials and compounds. Figures 1.1 and 1.2 show the ranges of elas-tic and inelastic neutron scattering applications, compared with a number of othertechniques. There are clearly large areas of overlap as well as definite areas ofunique applications. Furthermore, when considering specific applications, such aslight elements or bulk magnetic scattering, neutrons have a unique role. Neutronscouple directly to mass and spin, and photons couple preferentially to and throughcharge distribution; these techniques are therefore complementary at a fundamentallevel.

One area of apparent competition might be in the high-energy, high-momentumtransfer region (top right corner of Fig. 1.2). Previously, this was only withinreach of inelastic neutron scattering, but developments of (triple-axis) X-ray inelas-tic scattering have now produced a large region of overlap. In specific cases, forexample, the measurement of phonon dispersion curves at high energies, neu-trons will always “struggle” because of their lower velocity. Consequently, in theoverlap region, photons would be the probe of choice. However, for comparablemeasurements in liquids and glasses, the different element specificity of the twotechniques makes them highly complementary for all but the simplest (elemental)systems. Developments of photon and neutron sources will further enhance thiscomplementarity.

Fig. 1.2 Inelastic neutron scattering provides information that covers a large area in space and time.Other techniques mainly cover different areas. With latest generation planned neutron sources inEurope, the ranges will extend in the directions indicated, filling in the “missing areas”. The dia-gram covers typical atomic length and time scales. Techniques that do not directly provide distanceinformation are indicated only as bars along the time axis. The time scale only refers to equilibriumphenomena. Non-equilibrium effects, such as those studied in “pump-probe” experiments at veryshort time intervals (fs) will always remain the domain of photon-based techniques [12]

1 Neutron Applications in Earth, Energy, and Environmental Sciences 7

1.3 Recent Neutron Applications in Earth, Energy,and Environmental Research

Neutron scattering and spectroscopy applications in the study of minerals, rocks,and environmental and energy-related materials stem from some unique merits ofneutrons, experimental techniques, and present-day neutron sources [13]. Theseadvantages become evident with the examples of applications reported in this vol-ume. The intent is to provide a guided introduction to the potential of these tech-niques in a variety of these related fields.

1.3.1 High Penetration Power

The low attenuation of neutron beams by many metals and materials has madeextreme sample environments (high temperature, high pressure, reaction cells, dif-ferential loading frames, etc.) easier to work with for neutron scattering. Theextreme conditions are often needed to simulate Earth surface and interior condi-tions (Fig. 1.3), and these conditions can be reproduced by environmental equipmentthat has little interference with the neutron beam, as compared with other exper-imental probes. High-temperature furnaces with Vanadium or Zirconium heatingelements are virtually transparent to thermal neutrons. High-pressure cells (also incombination with high temperature) allow access to large portions of the recipro-cal space through low-absorbing gaskets. Sample cells fitted with pressure- and

Fig. 1.3 Mineral crystal structures carry a record of their genesis, especially when studied underthe conditions at which they formed deep in the Earth. Structural models of common rock-forming minerals shown from the left are olivine, amphibole, pyroxene, mica, and garnet. Var-ious geodynamic environments are represented. MORB = Mid-Ocean Ridge Basalt; IAB =Island Arc Basalt; OIB = Ocean Island Basalt. The hydrous component of minerals and rockshas a great impact on all geodynamic processes (Picture courtesy of R. Oberti)

8 R. Rinaldi et al.

temperature-measuring devices can deliver accurate measurement conditions. Agood example of this is given by pressure cells with anvils made of BN lined withCd foil (which absorb the beam quite effectively) and gaskets made of TiZr alloy,which transmit neutrons directly through to the sample [14].

Other equipment for in situ experiments include reaction cells, differential load-ing frames, cryostats, etc., making it possible to study minerals, and other Earth,energy, and environment materials in their natural or non-ambient conditions andin a time-resolved mode. The transformations and reactions occurring in the diverseenvironments of formation can thus be explored and monitored directly and, impor-tantly, with access to details all the way down to atomic-scale resolution.

On the other hand, the weak interaction results in a low flux of the scatteredneutrons; hence, weak signals from small samples. This can be a limiting factor,especially in high-pressure studies where such limitations demand an increase insample size, which in turn increases the size of the apparatus toward practical andmechanical limits. The most suitable objects for neutron applications are thereforeeither bulky or gram-scale samples. The in situ and time-resolved studies describedin this monograph encompass a large number of possible applications in a varietyof fields.

Studies on natural minerals and their magnetism at high pressure and temperatureare reviewed by Redfern and Harrison (Chapter 4). Some fundamental features, suchas cation order–disorder and phase transitions in rock-forming minerals, are impor-tant in modeling the geological phenomena. The pressure range of current apparatusis still inadequate to match the first transition zone within the Mantle. However,there are no real limits to either temperature or reciprocal space exploration in high-temperature furnaces. The emphasis is therefore on simultaneous temperature andpressure cells, which offer otherwise unobtainable sets of conditions compared withother presently available techniques.

Due to the special instrumental requirements imposed by high-pressure experi-ments, special beam lines and devices have been or are planned at the new neutronspallation sources in the USA [SNAP, SNS] and Japan [15] to match pressures andtemperatures typical of crust to upper mantle environments. Pressures up to tens ofGPa and temperatures in excess of 2000◦K on ∼1-mm3 samples are envisaged on aroutine basis. Many opportunities exist with regard to both technical improvementsand scientific advancements in this field.

Clays, their water content, and the transformations they undergo upon hydrationand dehydration are reviewed by Bihannic et al. (Chapter 18). The interlayer waterdynamics at the Angstrom scale are linked to the scale of landslides and slope insta-bility, and the arrangement of water in swelling clay is important to sorption of tracepollutants by clay liners. The chemical and physical behavior of contaminant sorp-tion materials requires an approach typical of a hierarchical structure (Triolo andAgamalian, Chapter 20), with properties ranging from those of solid nano-porousmedia to dispersed colloidal gels. Uptake of radioactive waste and other pollutantsby clay-like and nano-porous compounds is reviewed by Cuello et al. (Chapter 17).In situ studies are expected to provide a better understanding of the sorption proper-ties of clays and other minerals for radionuclide species and other organic pollutants.

1 Neutron Applications in Earth, Energy, and Environmental Sciences 9

1.3.2 Scattering Power for 1H and 2H

Neutrons, unlike X-rays, are efficiently and strongly scattered by hydrogen 1H anddeuterium 2H atoms. The hydrous component is of paramount importance in Earthcompounds and related processes. All biological materials as well as many mineralshave a structural hydrous component in the form of hydroxyls or water molecules.Several energy-related materials, from zeolites to gas hydrates, whether natural orman-made, also fall into this category. The water carried by minerals in subductionprocesses [16], and existing at depth in the lower Mantle, could be equivalent to thatof several oceans [17–19]. Water in minerals (even nominally anhydrous minerals),rocks, magmas, and in all Earth materials generally strongly influences the behaviorand properties of these materials at scales from atomic to continental levels. Thecharacter of volcanic eruptions, ranging from highly destructive (Plinian) to rela-tively benign (Hawaiian), depends on the water content and overall chemistry of themagma involved.

Isomorphic substitution of deuterium (2H) for hydrogen (1H) may have to beadopted to limit the high background resulting from the strong incoherent scat-tering of hydrogen; a problem still felt in neutron powder diffraction at conven-tional sources, but more tolerable in single-crystal work and at present-day neutronsources.

The study of the hydrous component in minerals and Earth materials by neutronscattering methods, reviewed by Gies (Chapter 7) and addressed in several otherchapters, ranges from nominally anhydrous mantle minerals to highly hydratednatural and industrial zeolites and clay minerals. Neutron scattering of these lattermaterials provides accurate determinations of water molecules in the structure (dis-tributed in channels, cages, and interlayer spaces) and their dynamics in response tochanges in physical and chemical environments.

Hydrogen has a fundamental role in many environmental issues and materi-als, from surface reactions in rocks and minerals (Ross et al., Chapter 8) to thecompounds related to the “Hydrogen Economy” (Celli et al., Chapter 14), andthe immense gas hydrate deposits within continental shelf sediments (Koza andSchober, Chapter 12). The stability of gas hydrates must be precisely determined byin situ structure studies under differing physical and chemical conditions to deriveaccurate predictive models of their stability in the geological environment, and todevise methods for tapping these very extensive energy resources.

The proton dynamics of highly dispersed materials is addressed by Albers andParker (Chapter 13). Applications include determining the proton-related surfacechemistry of nanomaterials used as reinforcing fillers of tires where improved safetyand reduced fuel consumption are at stake. Surface science studies consider adsorp-tion of hydrogen on nanodispersed precious metal particles as fuel cell catalysts.The occupancy of catalytically relevant sites provides essential information for tai-loring better catalysts. Surface deactivation of industrial catalysts by coke deposi-tion, chemical transformation of deposits, and other processes results in significantoperational loss at large-scale plants, which can be minimized by understanding themechanism of catalyst deactivation.

10 R. Rinaldi et al.

Hydrogen is also ubiquitous in biological materials, and its presence and distri-bution, either as an atomic species or in bulk, can be accurately investigated withneutrons. Johs et al. (Chapter 16) review neutron reflectivity methods for prob-ing interfacial interactions between proteins and minerals, which is significant inelucidating the structural changes involved in the microbiologic reduction of toxicmetals in the environment. Cuello et al. (Chapter 17) review the use of neutrons inwater pollutant speciation of both heavy metals and organic contaminants. Notableexamples are the hydration structure around Hg as a solute, or around lanthanidesadsorbed on clay minerals. In conjunction with X-ray methods, the uptake of Asby common sedimentary minerals has been characterized. Discussion of these prob-lems in the context of water strategies from governmental authorities provides directlinks with practical applications.

Sensitivity to hydrogen can also be used to good advantage for following waterdistribution and dynamics in many environments. This can include studies of poros-ity in rocks, concretes, and other media, as well as elucidating structures of plane-tary ices and hydrocarbon molecular structures. Triolo and Agamalian (Chapter 20)address the former using a combination of SANS and USANS techniques. Suchstudies may include phase transitions, such as the freeze-thaw cycles and otherdynamics in relation to sorbent and adsorbate properties. Other applications mayregard the experimental determination of the fractal dimension of volume pore sys-tems in hydrocarbon or water-containing rocks.

Cole et al. (Chapter 19) show how the behavior of fluids (polar and non-polar) inthe confined geometries of pores and fractures differs from the bulk. Many parame-ters, such as pore size, connectivity, and hydrophilic or hydrophobic character, mustbe taken into account, and both structural modifications and dynamic behavior canbe addressed by SANS and USANS techniques. Problems addressed range from thedesign of micro- or meso-porous media for industrial applications and the enhance-ment of oil recovery to CO2 sequestration in spent oil reservoirs.

In addition to hydrogen, other light elements are also amenable to accurate struc-tural determination by neutrons. Catti (Chapter 15) gives examples of lithium com-pounds in energy applications. The geochemical properties of such light elementsmerit investigation in natural minerals and geological materials, an opportunity thatwill certainly draw increased attention.

1.3.3 Iso-Electronic Species and High Q

The contrast in neutron-scattering cross-sections between isotopes (which is eithernone or very little in X-ray diffraction) offers many opportunities for structural stud-ies in mineralogical and environmental research. Additionally, since the scatteringcross-section for neutrons does not change with scattering vector (i.e., does not falloff as the inverse of the atomic radius), this permits the collection of diffraction dataup to large scattering vectors, thus providing a significant increase in the amountof information available in a diffraction pattern and to decouple the information onthermal motion and site occupancies.

1 Neutron Applications in Earth, Energy, and Environmental Sciences 11

Many common ions in minerals have equal or similar numbers of electrons. Forinstance, O2−, Na+, Mg2+, Al3+, and Si4+ present in most rock-forming silicateminerals possess, in these (mostly ionic) compounds, an effective maximum scatter-ing power for X-rays corresponding to the same number of 10 electrons. The sameapplies to Cl−, K+, Ca2+, Ti4+, all with 18 electrons. Other elements, such as Fe andMn, have several oxidation states, and are difficult to discriminate by X-ray scatter-ing. All of these are readily resolved by neutron diffraction with direct determinationof their site occupancies and order–disorder distributions in the crystal structures.The “high-Q” advantage also provides structural parameters (i.e., occupancy andthermal motion) less affected by correlations, and offers high precision and accuracyfor the determination of bonding geometries in crystal structures. Recent studiesof mantle minerals have revealed fundamental properties that underpin major geo-dynamic events. Redfern and Harrison (Chapter 4) give examples of these studies.Much more work in conjunction with other techniques (X-ray diffraction, IR, NMR,etc.) is needed in this field to provide fundamental, complementary information.

1.3.4 Fundamental Structural Properties

Inelastic Neutron Scattering (INS), which is not subject to tight selection rules onmode symmetries and wave vectors, can be used to determine phonon-dispersioncurves and phonon densities of states to reveal the fundamental structural proper-ties of minerals and phase transformations under pressures and temperatures of theEarth’s interior. Applications of INS to in situ studies offer a unique opportunity forsolving fine structural details (atomic and proton dynamics, soft modes, etc.) and themodeling and interpretation of fundamental thermodynamic parameters. Choudhuryand Chaplot (Chapter 5) survey these studies and future needs with examples froma large variety of rock-forming minerals. These data are invaluable for geochemicalmodeling of Earth interior conditions that are beyond the reach of other experimen-tal techniques.

The properties of silicate melts are of fundamental importance for a thoroughunderstanding of some geological processes and to investigate the nature of glass,a material known for thousands of years and still deserving close scientific andtechnological attention. Meyer et al. (Chapter 6) review the physical and chemicalproperties of glass and silicate melts by using quasi-elastic neutron scattering andmolecular dynamics simulations. The interplay of intermediate range order, atomicdynamics, and properties of mass transport in alkali silicate melts give insights intothe mechanisms relevant to geology, petrology, and volcanology, as well as to glasstechnology.

Nanostructures and time-resolved surface reactions in minerals and their dynam-ics are reviewed by Ross et al. (Chapter 8). A combination of inelastic and quasi-elastic neutron scattering with molecular dynamics techniques provides insights intothe thermodynamic properties of adsorbed water on mineral surfaces and nanoparti-cles. This complementary approach potentially offers a complete description of theenergy, structure, and dynamics of the hydration layers present on the surface ofmineral nanoparticles that are an intrinsic part of the particles themselves.

12 R. Rinaldi et al.

1.3.5 Texture and Residual Stress Analysis

In quantitative texture analyses (and also for stress and strain measurements), thehigh penetration of neutrons and the availability of wide beams allow the investi-gation of large specimens, which produce global volume textures with high grainstatistics even on coarse-grained materials. Position-sensitive detectors and time-of-flight techniques provide reflection-rich diffraction patterns of polymineralic rockscontaining low-symmetry mineral constituents. Residual stress and strain analysisof geological materials requires the high accuracy and sensitivity that neutrons canoffer, since natural effects on rocks are orders of magnitude smaller than in techno-logical materials.

Stress and strain analysis and the mechanical behavior of geological materialsstudied in situ by the use of engineering apparatus (Covey-Crump and Schofield,Chapter 9) reveal the fundamental parameters of rock behavior motivated by thesearch for predictive seismological and tectonic models. The concomitant mechan-ics and chemistry of carbonate rocks and subsurface hydrates could tie in with globalwater and carbon cycles. Neutron diffraction applied to the study of the orientationdistribution function (texture) of crystallites within the bulk of multi-mineral rocksamples (Pleuger et al., Chapter 10) show the sequence of complex tectonic eventsin geologic time. The use of large samples, afforded by neutrons, provides high grainstatistics even on coarse-grained material and data from the undisturbed interior ofa three-dimensional sample rather than from a polished surface.

1.3.6 Magnetism

Natural ferri/o-magnets are common compounds in Solar System planets. Geolo-gists have long utilized the magnetic signatures of rocks and minerals to reconstructstratigraphic sequences, and much remains to be discovered regarding the mag-netic properties of many minerals. Neutrons are very sensitive to magnetic moment,making them effective probes to determine magnetic structure, collective magneticexcitation, and crystal field energy levels in many magnetic elements. Neutrondiffraction of magnetic minerals and materials was recently reviewed by Harrison[20]. Recent applications to minerals, and a future outlook including cation andmagnetic ordering in ilmenite-hematite solid solution and exolution mechanisms,are reviewed by Redfern and Harrison (Chapter 4). They investigate these prop-erties and report that slowly cooled rocks containing finely exsolved members ofthe hematite-ilmenite series have strong and extremely stable magnetic remanence,suggesting an explanation for some magnetic anomalies in the deep crust and onplanetary bodies that no longer retain a magnetic field, such as Mars. Magneticdiffraction with polarized neutrons on single crystals reveals two generations oflamellae with different magnetic properties within the same crystal. Future devel-opments are expected by magnetic diffraction studies at pressures and temperaturesof the Earth interior. Only neutrons with a wide coverage of reciprocal space, even

1 Neutron Applications in Earth, Energy, and Environmental Sciences 13

in the very taxing conditions of such bulky environmental apparatus, can providesufficiently accurate data to extract this information.

Many technological applications are based on the magnetic properties of mate-rials, and many recent discoveries have implications in the fields of Earth, energy,and environmental sciences. Staniland et al. (Chapter 21) provide an outlook of thepossibilities offered by neutron scattering for understanding the magnetic propertiesof bacteria in natural environments.

1.3.7 Direct Imaging

Although not strictly a scattering technique and still of somewhat limited resolu-tion, imaging by radiography and tomography with neutrons offers the advantageof a very high penetrating power. The trade-off in resolution, when compared withX-rays, can be compensated for by the precision of measurements made in large-scale experiments. Applications in the Earth sciences include studies of structuraland rheological properties of molten systems reproducing natural magmas, directlyinvestigated inside custom-built apparatus by neutron scattering and imaging meth-ods [21, 22], and the study of rock permeability, moisture transport, and porositydeterminations (Lehmann, Chapter 11). Digital neutron imaging is fast replacingthe traditional film technique, and energy selection by TOF techniques opens upnew perspectives. Advances are expected in many fields of application, from thedirect observation of functional properties in fuel cells to the adhesive propertiesof cold welding, to time-resolved studies and energy-selective imaging with Braggedge enhanced features, to stroboscopic imaging by coupling the process with thepulse frequency of the source. Earth science, energy, and environmental studies cangreatly benefit from these developments

In actual fact, the greatly expanding application of neutron imaging techniques,encompassing a large variety of fields, many of which are outside the scope of thisbook, merits a special treatment that will be covered by the next monograph in theSeries.

1.4 Concluding Remarks

Studies utilizing neutron scattering techniques have many diverse applications inEarth, energy, and environmental sciences. They derive from a number of advan-tages offered by neutrons over other experimental techniques. Among these thesensitivity of neutrons to hydrogen plays a prominent role. By complementing andextending other research techniques, including X-ray analysis, these applicationsreveal many promising areas of enquiry. The aim of this monograph is to provideexamples of recent progress, evaluate current developments, and consider futureadvances in this expanding field of scientific research.

14 R. Rinaldi et al.

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