Table Of ContentTHEAQUEOUSPROCESSINGOFBARIUMTITANATE:
PASSIVATION,DISPERSION,ANDBINDERFORMULATIONS
FORMULTILAYERCAPACITORS
By
ROBERTE.CHODELKA
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOFDOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1996
Dedicatedto:
mymotherandfather
EleanorandEdwardChodelka
and
mysisterandniece,brothers,anddog
TheresaandEricaRogers,DavidChodelkaandTimothyChodelka,andZor
inappreciationoftheirendlesssupport,guidance,patience,andbeliefinme.
ACKNOWLEDGMENTS
Iwouldliketotakethisopportunitytothankall ofthe people who made this
researchprojectnotonlypossible,butsuccessful. SincerethanksisextendedtoDr.James
H. Adair,mycommitteechairandadvisor,forhisscientificguidanceinacademicaffairs
andfatherlyadviceinpersonalmatters. Myrelationshipwithhimhasmademenotonlya
betterscientist,butabetterhumanbeing. Iwouldliketothanktheothermembersofmy
committee,Drs. RobertT. DeHoff,Brij M. Moudgil,andMichaelD. Sacks, fromthe
DepartmentofMaterialsScienceandEngineering,RussellS. DragofromtheDepartment
ofChemistry,andStephenA.Costantinofromthesponsorofthecurrentresearch,Cabot
PerformanceMaterials(CPM),Boyertown, PA. Withouttheiradviceandthemonetary
supportfromCPM,thisresearchwouldnothavebeenasuccess.
IwouldliketoacknowledgeDr.StanleyBatesandthestaffattheMajorAnalytical
InstrumentationCenter(MAIC)attheUniversityofFloridafortheiranalyticalsupportand
technical advice, specifically, the high resolution transmission electron microscopy
conductedbyDr.AugustoMorrone.
Iamgratefultoallmyfriends,bothpastandpresentcolleaguesinDr. Adair's
researchgroupandin the Department ofMaterials Science and Engineering, for their
technical advice and support. Special thanks goes out to Dr. Sridhar Venigalla,
Dr.MelanieCarasso,andsoontobeDrs. CraigHabegerandJeffKerchnerforproof-
readingmydissertation,aswellasPamHowellforhersupportandassistanceduringmy
enrollmentinthePh.D. programattheUniversityofFlorida. Inthetimesofneed,Ifelt
thatIcouldalwaysrelyonmyfriends. IwillneverforgetthecompetitiveHeartscard
games,thedepartmentalI.M.sportsteams,andthesocialfunctionsthatmademyyearsat
theUniversityofFloridaquiteenjoyable.
iii
Inclosing,Iwouldliketothankmymother,father,sister,niece,andtwobrothers
for the continuous support, guidance, and patience. Theirbelief in me enabled my
perseverance.
iv
TABLEOFCONTENTS
ACKNOWLEDGMENTS
iii
LISTOFTABLES viii
LISTOFFIGURES ix
ABSTRACT xvi
CHAPTERS
1. INTRODUCTION 1
1.1. Introduction 1
1.2. LiteratureReview 2
1.3. ChemicalPassivationoftheBariumTitanateParticleSurfaceviaOxalic
Acid 4
1.4. DispersionofAqueousBariumTitanateSuspensions 5
1.5. BinderFormulations 6
1.6. ConclusionsandFutureWork 7
2. LITERATUREREVIEW 8
2.1. Introduction 8
2.2. ProcessingofMultilayerCapacitors 8
2.3. AqueousEnvironment 15
2.3.1.SolubilityofBariumTitanateandTitaniumDioxideinWater 15
2.3.2.PassivationofThermodynamicallyUnstableMetalsandGlasses 20
2.3.3.FeasibilityofPassivatingBariumTitanate 24
2.4. Dispersion 28
2.4.1.ElectrostaticSurfaceChargeFormationandStabilization 28
2.4.2.PolymericDispersion 36
2.4.3.ElectrophoreticBehaviorofTitaniumDioxideandBariumTitanate 38
2.4.4.ElectrophoreticBehaviorofCalciumOxalateMonohydrate 45
2.5. Binders 47
2.6. VariationsintheBa:TiRatioonSinteringofBariumTitanate 47
2.7. CharacterizationTechniques 50
2.7.1. SolutionChemistry 50
2.7.2. SurfaceChargeAnalysis 51
2.7.2.1. LightScatteringTechniques 53
2.7.2.2. ElectroacousticAnalysis 53
2.7.2.3. Sedimentationanalysis 54
v
2.7.3. ParticleObservation 54
2.7.3.1. ScanningElectronMicroscopy 54
2.7.3.2. TransmissionElectronMicroscopy 56
2.7.4. Viscosity 56
2.8. ChapterSummary 59
3. COXHAELMIICCAALCIPDAASDSDIIVTAITOINOSNOFTHEBaTi03PARTICLESURFACEVIA 62
3.1. Introduction 62
3.2. Approach 68
3.3. MaterialsandMethods 70
3.3.1. General 70
3.3.2. BariumTitanatePowderCharacterization 71
3.3.3. PreparationofAqueousBariumTitanateSuspensions 74
3.3.4. PreparationandCharacterizationoftheVariousBariumTitanate
PowdersforHighResolutionTransmissionElectronMicroscopy 75
3.4. ResultsandDiscussion 76
3.4.1. SolutionChemistryAnalysis 76
3.4.2. HighResolutionTransmissionElectronMicroscopyAnalysis 81
3.4.3. ElectrophoreticBehaviorofBariumTitanateSuspensionsat
VariousSolidsLoading 88
3.4.4. ElectrophoreticBehaviorofBariumOxalateMonohydrateand
BariumTitanateSuspensionsatVariousOxalicAcidConcentrations 92
3.4.5. ElectroacousticAnalysisofHighSolidsLoadingBariumTitanate
Suspensions 95
3.5. Conclusions 98
4. DISPERSIONOFAQUEOUSBaTi03SUSPENSIONS 101
4.1. Introduction 101
4.2. Approach 106
4.3. MaterialsandMethods 107
4.3.1. PreparationofLowSolidsLoadingBariumTitanateSuspensions 107
4.3.2. HighSolidsLoadingBariumTitanateSlurries 109
4.3.2.1. PreparationofBariumTitanateSlurries 109
4.3.2.2. CharacterizationoftheBariumTitanateSlurries 112
4.4. ResultsandDiscussion 113
4.4.1. PreliminaryStudiesatLowSolidsLoading 113
4.4.1.1. SolutionChemistry 113
4.4.1.2. SedimentationResults 116
4.4.1.3. ElectrophoreticBehavior 123
4.4.2. HighsolidsloadingBariumTitanateSlurries 125
4.5. Conclusions 135
5. BINDERFORMULATIONSFORTHEOXALATE/POLYETHYLENE
IMINE-TREATEDBaTi0 SUSPENSIONSFORMULTILAYER
CAPACITORS 3 139
5.1. Introduction 139
vi
5.2. Approach 143
5.3. MaterialsandMethods 145
5.3.1. General 145
5.3.2. PreliminaryStudiesLowSolidsLoading 146
5.3.2.1. ElectrophoreticandSedimentationStudies 146
5.3.2.2. PolymerInteractions 147
5.3.3. HighSolidsLoadingBariumTitanateSlurries 148
55..33..33..12.. PChraerpaacrtaetriioznatoifoBnaoTfit0he3SBlaurririuemsTwiittahnaBtienSdleurrrPireessent 114488
5.4. ResultsandDiscussion 149
5.4.1. PreliminaryStudiesatLowSolidsLoading 149
5.4.1.1. ElectrophoreticandSedimentationStudies 149
5.4.1.2. PolymerInteractions 151
5.4.1.3. TitrationCurves 155
5.4.2. HighsolidsloadingBaTi03Slurries 163
5.5. Conclusions 171
CONCLUSIONSANDSUGGESTIONSFORFUTUREWORK 175
6.1. Conclusions 175
6.2. SuggestionsforFutureWork 178
APPENDIXA 180
LISTOFREFERENCES 186
BIOGRAPHICALSKETCH 195
vii
LISTOFTABLES
Table page
3.1. SummaryofthechemicalconstituentsandpHrangesusedforanalyzing
17oBaTiOjsuspensionsviaelectroacousticanalysis 75
5.1. cSoummpmosairtyiono,fatnhderhseaomlpolgeicadlespirgonpaetritoine,s(waepipgahretntpevricsecnotsitByaaTnid03B,inbignhdaemr
yfioerlmdulaptoiinotn)s for the oxalate/polyethylene imine-treated BaTi03 slurry 165
A.l. Summary of the chemical constituents and physical characteristics for
BaTiOjslurriespreparedwith0.5w/ooxalicacid,andvaryingamountsof
polyethyleneimine(PEI)withoutbinderpresent 181
A.2. Summary of the chemical constituents and physical characteristics for
BpoalTyie0th3yslleunrreiiemsinpere(pPaErIe)dwwiitthhou1t.b0iwn/odeorxaplriecseanctid,andvaryingamountsof 182
A.3. Summary of the chemical constituents and physical characteristics for
BpoalTyie0th3yslleunrreiiemsinpere(pPaErIe)dwwiitthhou2t.b0i7nodeorxaplriecseanctid,andvaryingamountsof 183
A.4. Summary of the chemical constituents and physical characteristics for
BpoalTyie0th3yslleunrreiiemsinpere(pPaErIe)dwwiitthhou3t.0biwn/odeorxaplriecseanctid, andvaryingamountsof 184
A.5. Summary of the chemical constituents and physical characteristics for
BpoalTyie0th3yslleunrreiiemsinpere(pPaErIe)dwwiitthhou5t.b0i7nodeorxaplriecseanctid,andvaryingamountsof 185
viii
LISTOFFIGURES
Figure page
2.1. Productionflowchartforthefabricationofthemultilayercapacitor.'5' 9
2.2. Schematicshowingboththe3-dimensionalviewandtheside-viewofthe
laminated polycrystalline ceramic and metal structure of the multilayer
capacitor.**2' 10
2.3. Different types of rheological behavior characteristics for various
suspensions. 13
2.4. TheoreticalphasestabilitydiagramfortheBa-Ti-C02-H20system.04'15' 17
2.5. ThetheoreticalstabilitydiagramforaqueousTi02suspensions.'54'55' 18
2.6. bSacrhiemuamtitictasnuatmem,arsipezciinfigcatlhleyprtoheblienmcsoansgsrouceinatteddiswsiotlhutaiqouneooufsBprao2c+esasnidngtohef
formation of the Ti-rich and Ba-rich surface layer depicted in the
correspondingparticlediagram.04,35' 19
2.7. Sstcrhuecmtaurtei.c022s1h'owing two different views of the BaTi03 perovskite 21
2.8. Aschematic ofthe various techniques with corresponding reactions to
passivatemetalswhere(a)anoxidesurfacelayerformsinthepresenceof
0as2s,u(rbe)ctahatthotdhiecpgraoltveacntiiconcewlhlicmhakiensvoltvheespaipsealcirinfeictiahlemcaagthnoedsei,um(c)anaondoeditco
protection which passivates through exposure ofthe metal to a highly
concentratedoxidizingsolution,and (d)inhibitorionsassociate with the
surfacetoprotecttheunderlyingmetalfromcorrosion.158' 23
2.9. Fivedifferenttypesofglasssurfacesproducedduringcorrosion.*59' 25
2.10.SCpae-cCia2t0i4o-nH2d0iasgyrsatmesm/f6o3r'64'(a) the Ba-C2O4-H20 system03'58' and (b) the 27
2.11 Theseparationdistance,d,betweenthetwopairsofparticlesisdetermined
atthe initial interaction ofthe surrounding ionic clouds. The effective
thicknessofthesurroundingioniccloud(diffuselayer)isthereciprocalof
theDebye-Hiickelparameterwherethekvaluein(a)issmallerthan(b) 31
2.12.Thepotentialdistributionnearthesurfaceofaparticlefordifferentionic
strengthvaluesforasimpleGouy-Chapmanmodelofthedoublelayer.'70' 32
ix
2.13.Theelectricaldoublelayerstructureshowingthe strongly adsorbed ions
withintheSternplaneandthediffusesurroundingcloudofcounterionsthat
decreasesinconcentrationwithdistancefromtheparticlesurface/68' 34
2.14.(a.) Aschematic showing the attractive, repulsive and total electrostatic
interactionenergycurvesforaspecificsolutionconditions,and(b.)thetotal
electrostatic interaction energy curves for apoorly dispersed system, a
moderatelydispersedsystem,andawelldispersedsystem.'68,70' 35
2.15.Schematic showing a possible interaction between aqueous species,
specificallyaPVA-Ba2+interaction/44'45' 37
2.16.Schematic showing two differentpolymeric dispersing mechanisms for
suspensions,(a)depletiondispersionwherethepolymerremainsinsolution
and prevents particle collisions and (b) adhesion of the cationic
polyelectrolytetotheparticlesurfacepreventingparticle-particlecontactby
bothpolymericandelectrostaticrepulsion/38' 39
2.17.e(aa)rtShucmamtiaornysaotf0t.h3e3mxob1i0"l3iMtycvosn.cpenHtrcautrivoens,f(obr)thEelercuttriolpehaotredtiifcfermeonbtilailtkyalvisn.e
pH curves for rutile in the presence of different concentrations of
Ba(N03)2.(7284' 41
2.18.PthaarttisclheowelsecvtarroipahtoiroensiinsldoatttaofloortvbaerhiaovuisorloatsswoefllcoamsmtehrecpiaolwdBearTsiu0p3plpioewr/d4e9'r 43
2.19.Elloeacdtirnogp/h4o9r'eticbehaviorforthreeBaTi03suspensions at different solids 44
2.20.BoththetheoreticalandexperimentalelectrophoreticbehaviorofCOMare
illustratedandarelativelyconstantchargeisdepictedoverthepH range
fromPH4topH10/64' 46
2.21.t(ao.)deStcehremmianteicthreepelreecsternotpihnogretthiecpamrotbiicllietmy,ove(bm.e)nTtheinealnecatprpolpiheodreetliecctmroicbifliietlyd
canbeplottedasafunctionofpHorusedtocalculatethezetapotentialand
plottedasafunctionofpH 52
2.22.Schematicshowingvariationsinthesedimentationofthesuspensions and
thesedimentheightrecordedinthesedimentationanalysis. Fingershows
variationsinthetransparencyofthesuspensions 55
2.23.Scanningelectronmicrographsoftheparticlepackingwithinthehandcast
pseudo-tapesshowingthedifferencebetween(a.)gooddispersionand(b.)
baddispersion 57
2.24.Schematicshowingthevariouscomponentsandmathematicalvariablesfor
thecone/plateviscometerandthecorrespondingmathematicalexpressions
todeterminetheshearstress,shearrate,andviscosity/105' 58
2.25.Aparstiucmlemsa,rwyatoefr,vaarnidopusoliynmteerraicctiaodndsittihvaetscantakeplacebetweentheBaTi03 60
x
