Surface Diffusion: Metals, Metal Atoms, and Clusters

779 Pages·2010·15.72 MB·English

by  Grażyna Antczak, Gert Ehrlich

Surface Diffusion
Metals,MetalAtoms,andClusters
For the first time, this book unites the theory, experimental techniques, and computa-
tionaltoolsusedtodescribethediffusionofatoms,molecules,andnanoparticlesacross
metal surfaces. Starting with an outline of the formalism that describes diffusion on
surfaces,theauthorsguidethereaderthroughtheprinciplesofatomicmovement,before
moving on to describe diffusion under special circumstances, such as the presence of
defects or foreign species. With an initial focus on the behavior of single entities on a
surface, later chapters address the movement of clusters of atoms and the interactions
betweenadatoms.Whilethereisaspecialemphasisonexperimentalwork,attentionis
paid to the increasingly valuable contributions theoretical work has made in this field.
This book has wide interdisciplinary appeal and is ideal for researchers in solid state
physicsandchemistry,aswellasmaterialsscienceandengineering.
Graz·yna Antczak is a Humboldt Fellow in the Solid State Physics Department at
Leibniz University, Hannover, Germany. She received her Ph.D. from the Institute of
ExperimentalPhysicsattheUniversityofWrocław,Poland,wheresheisnowanadjunct
researcher.Dr.AntczakisaMemberoftheAmericanPhysicalSocietyandtheAmerican
VacuumSociety,andhashad15publicationsinscientificjournals.
GertEhrlichiscurrentlyResearchProfessorintheDepartmentofMaterialsScienceand
Engineering at the University of Illinois, Urbana-Champaign. He is internationally
recognizedasapioneerintheareaofsurfacediffusion,andhehasreceivednumerous
scientifichonoursandawards.Dr.Ehrlichisanactivememberofvarioussocieties,andis
aFellowoftheAmericanPhysicalSocietyandtheNewYorkAcademyofSciences.He
has written almost 200 journal articles and has served on several editorial advisory
boards.

Surface Diffusion
Metals, Metal Atoms, and Clusters
GRAZ˙YNA ANTCZAK
LeibnizUniversita¨tHannover,Germany
GERT EHRLICH
UniversityofIllinois,Urbana-Champaign
cambridge university press
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Firstpublished2010
PrintedintheUnitedKingdomattheUniversityPress,Cambridge
AcatalogrecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloginginPublicationData
Antczak,Grażyna,1973–
Surfacediffusion:metals,metalatoms,andclusters/GrażynaAntczak,GertEhrlich.
p. cm.
ISBN978-0-521-89983-3(hardback)
1. Diffusion. 2. Metals–Surfaces. 3. Surfaces(Physics) I. Ehrlich,Gert. II. Title.
QC176.8.D5A58 2010
530.4′15–dc22
2009050502
ISBN978-0-521-89983-3Hardback
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Contents
Preface pageix
Listofabbreviations xi
Listofsymbols xiv
1 Atomicdiffusiononsurfaces 1
1.1 Diffusivities:anintroduction 1
1.2 Distributionofatomicdisplacements 7
1.3 Jumprates 17
2 Determinationofadatommovements 24
2.1 Fieldionmicroscopy 24
2.2 Fieldelectronemissionmicroscopy 29
2.3 Scanningtunnelingmicroscopy 31
2.4 FIMmeasurementofdiffusivity 34
2.5 Displacementdistributions 44
2.6 STMmeasurementsofdiffusion 46
2.7 Othermeasurementtechniques 53
2.8 Theoreticalestimates 56
3 Atomiceventsinsurfacediffusion 64
3.1 Adatombindingsites 64
3.2 Atomicjumpsindiffusion 86
3.3 Longjumpsinsurfacediffusion 116
3.4 Transientdiffusion 146
4 Diffusiononone-dimensionalsurfaces 183
4.1 Aluminum:Al(110),(311),(331) 184
4.2 Nickel:Ni(110) 186
4.3 Nickel:Ni(311)andNi(331) 193
4.4 Copper:Cu(110),Cu(311),Cu(331) 194
4.5 Molybdenum:Mo(211) 200
vi Contents
4.6 Rhodium:Rh(110),(311),(331) 202
4.7 Palladium:Pd(110),(311),(331) 204
4.8 Silver:Ag(110),(311),(331) 207
4.9 Tungsten:W(211) 211
4.10 Tungsten:W(321) 225
4.11 Iridium:Ir(110),(311),(331) 227
4.12 Platinum:Pt(110),(311),(331) 230
4.13 Gold:Au(110),(311),(331) 235
4.14 Lead:Pb(110) 238
4.15 Tablesfor1DDiffusion 238
5 Diffusionontwo-dimensionalsurfaces 261
5.1 Aluminum:Al(100) 261
5.2 Aluminum:Al(111) 265
5.3 Potassium 269
5.4 Iron:Fe(100),(111),(110) 269
5.5 Nickel:Ni(111) 274
5.6 Nickel:Ni(100) 277
5.7 Copper:Cu(100) 283
5.8 Copper:Cu(111) 295
5.9 Molybdenum:Mo(110),(111),(100) 301
5.10 Ruthenium:Ru(0001) 304
5.11 Rhodium:Rh(111),(100) 304
5.12 Palladium:Pd(100) 309
5.13 Palladium:Pd(111) 312
5.14 Silver:Ag(111) 315
5.15 Silver:Ag(100) 322
5.16 Tantalum:Ta(110) 328
5.17 Tungsten:W(110) 329
5.18 Tungsten:W(100) 341
5.19 Tungsten:W(111) 344
5.20 Rhenium:Re(0001) 347
5.21 Iridium:Ir(111) 348
5.22 Iridium:Ir(100) 353
5.23 Platinum:Pt(111) 355
5.24 Platinum:Pt(100) 361
5.25 Gold:Au(100) 365
5.26 Gold:Au(111) 368
5.27 Lead:Pb(111) 372
5.28 Bismuth:Bi(111) 372
5.29 Tablesfor2Ddiffusion 373
5.30 Predictionsandcomparisons 402
Contents vii
6 Diffusioninspecialenvironments 423
6.1 Nearimpurities 423
6.2 Todescendingstepedges 430
6.3 Atomlifetimeversusthestep-edgebarrier 479
6.4 Comparisons 485
6.5 Atomdescentovermany-layeredstepsandbetweenfacets 487
6.6 Toascendingstepedges 498
6.7 Diffusionneardislocations 506
7 Mechanismofclusterdiffusion 517
7.1 Viasingleatomjumps 520
7.2 Concerteddisplacements 536
7.3 Mechanismofdimerdiffusionversusbondlength 546
7.4 Kineticmechanismsoflargerclusters 547
7.5 Derivationofthemechanismoflargeclustermovements 550
8 Diffusivitiesofsmallclusters 556
8.1 Earlyinvestigations 556
8.2 Clustersonaluminumsurfaces 561
8.3 Clustersonironsurfaces 567
8.4 Clustersonnickelsurfaces 569
8.5 Clustersoncoppersurfaces 575
8.6 Clustersonrhodiumsurfaces 593
8.7 Clustersonpalladiumsurfaces 596
8.8 Clustersonsilversurfaces 598
8.9 Clustersontantalumsurfaces 601
8.10 Clustersontungstensurfaces 602
8.11 Clustersonrheniumsurfaces 618
8.12 Clustersoniridiumsurfaces 619
8.13 Clustersonplatinumsurfaces 634
8.14 Clustersongoldsurfaces 647
8.15 Comparisons 651
9 Diffusionoflargeclusters 664
9.1 Largeclustersonfcc(100)surfaces 664
9.2 Largeclustersonfcc(111)surfaces 676
9.3 Largeclustersonfcc(110)surfaces 692
9.4 Commentsandcomparisons 693
viii Contents
10 Atomicpairinteractions 696
10.1 Earlymeasurements 698
10.2 Morerecentstudies 704
10.3 Summary 730
Appendix:Preparationofsamplesforfieldionmicroscopy 735
Index 743
Thecolorplatesaresituatedbetweenpages298and299.
Preface
Surface diffusion on metals has been a subject of scientific interest for roughly ninety
years.Duringthefirstfortyyearsofthisperioditwasveryhardtodomeaningfulwork
because of technical problems – the difficulty of establishing good enough vacuum
conditions to maintain a surface clean for measurements. In a few laboratories,mostly
industrial,ultrahighvacuumtechniqueswerealreadypracticedatthattime,butthiswas
not the normal course of events. All of this changed after World War II, first with the
general adoption of good vacuum practices, and then with the development of more
capabletechniquesforexaminingkineticprocessesthatareimportantonasurface.The
first ofthesetechniqueswas field ionmicroscopy,invented byErwinMüller[1,2],the
first method to provide a direct view of single atoms on a surface. The next important
developmentwasthescanningtunnelingmicroscope,devisedbyBinnigandRohrer[3],
whichestablishedthecapabilityofprobingalargescalesurfacewithhighresolution.The
lastmajorcontributionwastheprogressintheoreticaltechniquesandcomputertechnol-
ogy,whichtowardtheendofthetwentiethcenturyledtotherapidgrowthoftheoretical
calculations.
Thelastfortyyearshavethereforebeenatimeofgreatprogressinourunderstanding
of surface diffusion, especially of metal atoms on metals. These advances have been
spread over the scientific literature, and there has been no overview of the entire field,
which is what we are trying to provide here. Our primary emphasis will be on experi-
mentalworktodefinetheprocessesparticipatinginsurfacediffusion.However,theore-
ticalworkcannowbedonesoexpeditiouslythatithasprovidedvaluableguidance,and
is now being intensively pursued. As such these contributions will also be carefully
noted.1Surfacediffusionhas,ofcourse,alonghistory,datingbacktotheinitiatingwork
ofHamburger[5]in1918.Theseearlystudieshave,however,alreadybeenreviewed[6],
so here we will be concerned with work on surface diffusion under ultra high vacuum
(UHV)conditionsandonanatomicscale,whichbeganinthe1960s,andhasledtothe
currentstateofunderstanding.
Thebeginningsofmodernstudiesofsurfacediffusionweregreatlyinfluencedbythe
insightsandinspirationofDavidTurnbull,aswellasbythetraditionsandexpertiseat
General Electric. We have also benefited from the encouragement and suggestions of
Ryszard Błaszczyszyn, and were able to draw on the expertise at the Institute of
ExperimentalPhysicsoftheUniversityofWrocław.Here,attheUniversityofIllinois,
1 Forareviewoftheoreticalefforts,seeT.Ala-Nissilaetal.[4].