Principles and Applications of Powder Diffraction

397 Pages·2008·186.158 MB·English

by  Abraham Clearfield, Joseph Reibenspies, Nattamai Bhuvanesh

Principles and Applications of
Powder Diffraction
Principles and Applications of Powder Diffract i on. Edited by Abraham Clearfield, Joseph H. Reibenspies
and Nattamai Bhuvanesh © 2008 Blackwell Publishing Ltd. ISBN: 978-1-405-16222-7
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Dedication
Asthesayinggoes,weallstandontheshouldersofthegiantswhoprecededus.
I, Abraham Clearfield, remember the first lecture I heard where Linus Pauling described
thestructureofsilicatesandhowitwouldbepossibletounderstandlifeprocessesthrough
solvingthestructuresofbiologicalmolecules.Ithenhadthegoodluckofworkingwithone
ofPauling’sstudents,PhilipA.Vaugan,formydoctorate.Welearnedourcrystallography
frombooksbyMartinJ.BuergerandsolvedstructuresusingPatterson’smethod.Ihadthe
goodfortunetohearthefirstpresentationofHauptmanandKarle’sdirectmethodsatthe
ACA meeting held at the University of Michigan. To these and other leaders in the field
Iamgrateful.OfcourseIwouldberemisstonotsimilarlydedicatethisbooktomywife
RuthwhourgedmetogoontoearnaPhDandhasalwaysbeenmyadvisorandsteadfast
supporter.
I,JosephH.Reibenspies,wishtodedicatethisbooktomyparents,JohnandClaire,who
gave me life and taught me to love learning. I also dedicate this book to my advisor and
friendOrenAnderson,whotaughtmetolovescience.FinallyIdedicatethisbooktomy
wifeLisa,whotaughtmethemeaningofloveandwillalwaysbetheloveofmylife.
I,NattamaiBhuvanesh,wouldliketodedicatethisbooktomyparents,mybrothers,my
wifeandkids,myteachers,andtoallthosewhopresentedmewithinterestingchallenges
inscience.
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Principles and Applications of
Powder Diffraction
Edited by
Abraham Clearfield
Texas A & M University, USA
Joseph H. Reibenspies
Texas A & M University, USA
Nattamai Bhuvanesh
Texas A & M University, USA
A John Wiley and Sons, Ltd, Publication
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Thiseditionfirstpublished2008
©2008byBlackwellPublishingLtd
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Clearfield,Abraham.
Principlesandapplicationsofpowderdiffraction/AbrahamClearfield,JosephReibenspies,
NattamaiBhuvanesh.–1sted.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN-13:978-1-4051-6222-7(hardback:alk.paper)
ISBN-10:1-4051-6222-8(hardback:alk.paper)
1.X-rays–Diffraction–Measurement.2.Powders–Opticalproperties.I.Reibenspies,Joseph
Henry.II.Bhuvanesh,Nattamai.III.Title.
QC482.D5C532008
(cid:1)
548.83–dc22
2008002548
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Setin10/12ptMinionbyNewgenImagingSystemsPvt.Ltd,Chennai,India
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1 2008
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Contents
Preface ix
ListofContributors xi
1 AnOverviewofPowderDiffraction 1
LachlanM.D.Cranswick
1.1 Introduction 1
1.2 Rangeoffieldsusingpowderdiffraction 6
1.3 Advantagesofpowderdiffraction 6
1.4 Limitationsofpowderdiffraction 17
1.5 Pitfalls,misconceptionsandrequirements 28
1.6 Comparisontosingle-crystaldiffraction 32
1.7 Applicationsusingpowderdiffraction 37
1.8 Conclusion 58
Acknowledgments 58
References 58
AppendixA.1Listofavailablesoftwarerelevanttopowderdiffraction 62
2 IntroductiontoDiffraction 73
AbrahamClearfield
2.1 IntroductiontoX-raydiffraction 73
2.2 Solvingthegeometricproblem 77
2.3 ScatteringtheoryandtreatmentofX-raydiffractiondata 88
2.4 Theintensityformula(Nuffield,1966) 95
2.5 Thereciprocallattice(Buerger,1942;LaddandPalmer,2003) 97
2.6 Crystalsymmetryandspacegroups(Buerger,1971;Hammond,2004) 102
References 121
3 PracticalAspects 123
JosephH.ReibenspiesandNattamaiBhuvanesh
3.1 GenerationofX-rays:generalconceptsandterminology 123
3.2 Typicallaboratoryexperimentalsetups 126
3.3 X-rayoptics:monochromatorsandGöbelmirrors 132
3.4 DetectionofX-rays:generalconceptsandterminology 132
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vi Contents
3.5 Specimenmountingmethods:generalconceptsandterminology 143
3.6 Datacollection:generalconcepts 150
3.7 Pitfallsanderrors 154
References 155
4 ProfileAnalysis 158
ArntKern
4.1 Introduction 158
4.2 Originoflineprofileshapes 158
4.3 Convolution-basedprofilefitting 178
References 196
5 IntroductiontoNon-LaboratoryRadiationSources 199
PeterJ.ChupasandKarenaW.Chapman
5.1 Introductiontonon-laboratoryradiationsources 199
5.2 Synchrotronradiationinstrumentation 209
5.3 Neutrondiffractioninstrumentation 217
5.4 Resources 223
References 223
6 PhaseIdentificationandQuantitativeMethods 226
PamelaWhitfieldandLyndonMitchell
6.1 Introduction 226
6.2 SamplepreparationforphaseIDandquantitativeanalysis 227
6.3 Datacollection 234
6.4 Powderdiffractionasafingerprintmethod 236
6.5 Phasematchingusingthepowderdiffractionfile–search-match
routines 242
6.6 Profilefitting 246
6.7 Assigninghklsandcellparameterrefinement 248
6.8 Quantitativephasedeterminationintheabsenceofstructural
information 251
6.9 Conclusions 258
Acknowledgment 258
References 259
7 StructureSolution 261
ArmelLeBail
7.1 Anoverviewofstructuresolutionbypowdermethods 261
7.2 Indexingapowderdiffractionpattern:abottleneck 264
7.3 Spacegroupdetermination,intensitiesextraction 274
7.4 Classical(Pattersonanddirect)methodsofstructuresolution 280
7.5 Directspacemethodsofstructuresolution 289
7.6 Structurepredictionandpowderdiffraction 297
7.7 Structuresolutionfrommultiplepowderpatternsandmultiple
techniques 299
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Contents vii
7.8 Conclusion 301
References 302
8 StructureRefinement 310
JamesA.Kaduk
8.1 AnintroductiontoRietveldrefinement 310
8.2 Statisticalandgraphicalmeasuresofarefinement 311
8.3 Functionsfordescribingpeakshapes,backgrounds,anddiffuse
scattering 317
8.4 Refinementstrategies 323
8.5 UseofchemicalknowledgeinRietveldrefinement–organicexamples 326
8.6 UseofchemicalknowledgeinRietveldrefinement–inorganicexamples 332
8.7 X-ray/neutroncombinedrefinement–inorganicexamples 346
8.8 QuantitativeanalysisbyRietveldrefinement 352
8.9 LimitationsofRietveldrefinement 360
Acknowledgments 361
References 361
9 OtherTopics 365
E.AndrewPayzant
9.1 Size/straindetermination 365
9.2 Non-ambientdiffractionmethods(temperature,pressure,humidity) 369
9.3 Insitudiffractionexperiments 372
9.4 AnintroductiontoPDFanalysis 376
9.5 Summary 378
References 378
Index 381
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Preface
Powderdiffractionhasbeenthestapleanalyticaltoolforchemistsandmaterialsscientists
formorethan50years.Powderdiffractionisatooltoidentifyandcharacterizematerials
by analyzing the radiation scattering produced when the materials are illuminated with
X-raysorneutrons.Thepatternsformedbythescatteredradiationprovideanabundance
ofinformationfromsimplefingerprintingtocomplexstructuralanalysis.Thisworkwill
introducethereadertotheworldofpowderdiffraction,whyitworksandhowitworksandin
theendwhatyoucanandcannotdowithit.Someofthetopresearchersinthefieldofpowder
diffraction have collaborated on this work to bring the reader the most comprehensive
source on the subject. The following paragraphs describe some of the information the
reader may find in this work as well as a guide to how to best use the material that is
presented.
Chapter1containsashortoverviewoftheinformationobtainableusingmodernpowder
diffraction methods to stimulate the reader’s interest. The main topics of later chapters
(phaseidentification,structuresolution,Rietveldrefinementandnon-ambientmethods)
willbeintroducedinoutlineusingexamplesfromtheworldofpharmaceuticals,organic
and inorganic materials. The limitations of powder diffraction will be detailed as well as
comparisonstosingle-crystaldiffractionmethods.
Chapter2containsallthetheoryrequiredtounderstandlaterchaptersandiswrittenat
a level suitable for readers following or with an undergraduate science degree. The basic
phenomenonofdiffractionfromaperiodicarrayleadingtoBragg’slawisdeveloped.The
morerigorousderivationoftheLaueequationsandtheirvisualizationviatheEwaldsphere
willthenbeintroducedtohelp“demystify”theconceptofthereciprocallatticeanditsuse
incrystallography.Thechapterdescribesthebasicelementsofsymmetryandspacegroups
inthesolidstateandtheuseofInternationalTablesinpowderdiffractionproblems.
Chapter3containsthepracticalinformationneededtoperformsuccessfulpowderdif-
fractionmeasurementsusinglaboratory,synchrotronandneutronsources.Thegeneration
ofX-raysbytypicallaboratorysourcessuchassealedtubesandrotatinganodesisdiscussed.
ModernX-raydetectorsincludingscintillation,solid-state,linearposition-sensitivedetect-
orsandareadetectorsarehighlighted.ThegeneralX-raydiffractionexperimentalsetups,
suchastheBragg–Brentanoandtransmissiongeometrywhichareofutmostimportance
is discussed. Focused, para-focusing and pinhole X-ray beams and their applications to
normalandmicro-diffractionisincluded.Samplemountingandmeasuringproceduresare
described.
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x Preface
Chapter4discussesthegeneralareaofpowderdiffractionprofileanalysis,whichincludes
factors, which affect peak intensity, position and shape. The resolution of the profiles
alongwithadiscussionofthevariousprofileanalysisfunctions,includingthefundamental
parametersapproachareexplained.
Chapter 5 introduces the reader to “non-laboratory” radiation sources. The chapter
highlightstheadvantagesofhighbrilliancesynchrotronX-raysources.Abriefdescription
ofthestate-of-the-artneutroninstrumentationwindsupthechapterandfinallyadiscussion
onthegeneralusesofneutronpowderdiffractionconcludesthechapter.
Chapter6describessomeofthe“classical”applicationsofpowderX-raydiffractionto
sampleidentificationanddeterminationofphasemixtures.Specializedfieldssuchashigh-
throughput screening and combinatorial analysis are discussed. The use of whole profile
analysis,includingcellrefinementandindicesassignmentisintegratedwithsearch-match
methodology. Finally, an overview of the methods for quantitative analysis of crystalline
andamorphouscontainingphasesisgiven.
Chapter7describesthetopicsofstructuresolutionfrompowderdiffractiondata.Each
stageofthestructuresolutionprocessisdescribedusingexamplesfrombothorganicand
inorganicsystems.Boththepotentialpowerofthemethodanditsinherentlimitationsare
described.ParticularexamplesofcombinedneutronandX-rayanalysisarehighlighted.
Chapter 8 covers topics on Rietveld refinement from powder diffraction data. Each
stage of the refinement process is described using examples from both organic and inor-
ganic systems. Both the potential power of the method and its inherent limitations are
presented.ParticularexamplesofcombinedneutronandX-rayanalysiswillbehighlighted.
QuantitativeanalysisbytheRietveldmethodisoutlined.
Chapter 9 presents a number of more specialized/advanced topics not considered in
detailelsewhereinthebook.Theseincludemethodsforsize/strainanalysisusingpowder
diffraction,methodsthathavebecomemorewidelyusedinnano-technologiesandnon-
ambientmethodsforstudyingmaterialsasafunctionoftemperature,pressure,humidityor
chemicalenvironment;insitumethodsforstudyingphasetransitionsorchemicalreactions
bypowderdiffraction;andtheopportunitiesforstructuralinsightgivenbypairdistribution
functionanalysis.
Theeditorstrustthatthereaderwillfindinthisbook,theelementsofX-rayandneutron
powderdiffractionthatarerelevanttohisorherparticularneeds.
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