Electroceramics: Materials, Properties, Applications

576 Pages·2003·7.264 MB·English

by  A. J. Moulson, J. M. Herbert

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Electroceramics
Second Edition

Electroceramics
Second Edition
Materials (cid:1) Properties (cid:1) Applications
A. J. Moulson
and
J. M. Herbert
Copyrightu2003 JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,
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CONTENTS
Preface xi
Acknowledgements xv
Glossary xvii
1: Introduction 1
2: Elementary Solid State Science 5
2.1 Atoms 5
2.2 Thearrangement of ionsin ceramics 10
2.3 Spontaneous polarization 17
2.4 Phase transitions 19
2.5 Defects incrystals 20
2.5.1Non-stoichiometry 20
2.5.2Pointdefects 21
2.6 Electrical conduction 24
2.6.1Chargetransportparameters 24
2.6.2Electronicconduction 26
2.6.3Ionicconduction 43
2.6.4Summary 47
2.6.5Schottkybarrierstoconduction 48
2.7 Charge displacementprocesses 52
2.7.1Dielectricsinstaticelectricfields 52
2.7.2Dielectricsinalternatingelectricfields 60
2.7.3Bariumtitanate–theprototypeferroelectricceramic 71
2.7.4Mixturesofdielectrics 72
2.7.5Impedancespectroscopy 85
Problems 90
Bibliography 92
3: Processing of Ceramics 95
3.1 General 95
3.2 Cost 96
3.3 Rawmaterials 96
3.4 Powderpreparation – mixing andgrinding 97
3.4.1The‘mixedoxide’orsolidstateroute 100
3.4.2Theoxalateroute 100
3.4.3Thealkoxideroute 101
3.4.4Hydrothermalsynthesis 101
Electroceramics:Materials,Properties,Applications.2ndEdition.EditedbyA.J.MoulsonandJ.M.Herbert.
&2003JohnWiley&Sons,Ltd:ISBN0471497479(hardback)0471497487(paperback)
vi CONTENTS
3.5 Calcination 101
3.6 Shaping 103
3.6.1Dry-pressing 104
3.6.2Isostatic-pressing 106
3.6.3‘Jolleying’ 107
3.6.4Extrusion 107
3.6.5Colloidalprocessing:slip-casting 108
3.6.6Tape-casting 109
3.6.7Calenderingandviscouspolymerprocessing 110
3.6.8Injection-moulding 111
3.6.9Filmsandlayers 111
3.7 High-temperature processing 114
3.7.1Densification 114
3.7.2Hot-pressing 115
3.7.3Isostatichot-pressing 116
3.7.4Glass-ceramics 117
3.8 Finishing 118
3.9 Porousmaterials 119
3.10 Processing andelectroceramics research anddevelopment 120
3.11 Thegrowth of single crystals 121
Problems 130
Bibliography 133
4: Ceramic Conductors 135
4.1 High-temperature heatingelements and electrodes 135
4.1.1Siliconcarbide 136
4.1.2Molybdenumdisilicide 141
4.1.3Lanthanumchromite 141
4.1.4Tinoxide142
4.1.5Zirconia 144
4.2 Ohmic resistors 145
4.2.1Thinfilms 146
4.2.2Thickfilms 147
4.3 Voltage-dependent resistors(varistors) 150
4.3.1Electricalcharacteristicsandapplications 150
4.3.2Siliconcarbide 156
4.3.3Zincoxide 156
4.4 Temperature-sensitive resistors 159
4.4.1Negativetemperaturecoefficientresistors(NTCthermistors) 160
4.4.2Positivetemperaturecoefficientresistors(PTCthermistors) 167
4.5 Fuelcells andbatteries 173
4.5.1Thestimulusfordevelopingfuelcellsandbatteries 173
4.5.2Basicsoffuelcellsandbatteries 176
4.5.3Electroceramicsforfuelcellsandbatteries 184
4.6 Ceramics-based chemicalsensors 198
4.6.1Sensorsbasedonsolidelectrolytes 199
4.6.2Gas-sensorsbasedonelectronicallyconductingceramics 207
4.6.3Humiditysensors 214
4.7 High transitiontemperature superconductors 217
4.7.1Overview 217
4.7.2Thephenomenonofsuperconductivity 218
4.7.3Ceramichigh-T superconductors(HTSs) 222
c
CONTENTS vii
4.7.4Theproperties,processingandapplicationsofHTSs 225
4.7.5Superconductingelectronics–thinfilms 233
4.7.6ThefutureforHTSs 235
Problems 236
Bibliography 240
5: Dielectrics and Insulators 243
PartI CapacitativeApplications 244
5.1 Background 244
5.2 Dielectricstrength 245
5.2.1Testconditions 246
5.2.2Breakdownmechanisms 246
5.3 Thermalshock resistance 250
5.4 Capacitors 251
5.4.1Capacitorcharacteristics 251
5.4.2Non-ceramiccapacitors 256
5.4.3Ceramiccapacitors 260
PartII PrincipalCeramic Types andApplications 269
5.5 Low-permittivity ceramic dielectrics andinsulators 269
5.5.1Electricalporcelains 269
5.5.2Alumina 276
5.5.3Beryllia 285
5.5.4Aluminiumnitride 286
5.5.5Ceramic‘packaging’technology 286
5.6 Medium-permittivity ceramics 289
5.6.1Rutileceramic 290
5.6.2Degradationintitanium-containingoxides 293
5.6.3High-powercapacitors 295
5.6.4Low-TCClow-losscapacitors 297
5.6.5Microwaveceramics 300
5.7 High-permittivity ceramics 310
5.7.1Modifiedbariumtitanatedielectrics 311
5.7.2Relaxorferroelectrics 320
5.7.3Multilayercapacitorswithbasemetalelectrodes(BME) 323
5.7.4Barrierlayercaps(ClassIV) 326
5.7.5Ferroelectricmemories 329
Problems 333
Bibliography 335
6: Piezoelectric Ceramics 339
6.1 Background theory 339
6.2 Parametersfor piezoelectric ceramics andtheir measurement 344
6.3 Generalcharacteristics andfabrication of PZT 354
6.3.1Effectsofdomains 354
6.3.2Effectsofaliovalentsubstituents 358
6.3.3FabricationofPZT 361
6.4 Importantcommercial piezoceramics 362
6.4.1Bariumtitanate 362
6.4.2Leadzirconate–leadtitanate(‘PZT’) 364
viii CONTENTS
6.4.3Lead-basedrelaxorpiezoelectricandelectrostrictiveceramics 366
6.4.4Leadniobate 369
6.4.5Lithiumniobateandlithiumtantalate 371
6.4.6Piezoceramic–polymercomposites 373
6.4.7Summaryofproperties 379
6.5 Applications 381
6.5.1Generationofvoltages 382
6.5.2Generationofdisplacement–‘actuators’ 386
6.5.3Highfrequencyapplications 396
6.5.4Piezoceramic–polymercomposites 402
6.5.5Summary 402
Appendix: Piezoelectricrelations for ceramics poled in the3 direction 404
Problems 407
Bibliography 409
7: Pyroelectric Materials 411
7.1 Background 411
7.2 Infrareddetection 413
7.3 Effectsof circuit noise 417
7.3.1Johnsonnoise 418
7.3.2Thermalfluctuations 418
7.4 Materials 419
7.5 Measurement ofthe pyroelectric coefficient 422
7.6 Applications 423
7.6.1Radiometry 424
7.6.2Pollutantcontrol 425
7.6.3Intruderalarm 425
7.6.4Thermalimaging 426
Problems 431
Bibliography 432
8: Electro-optic Ceramics 433
8.1 Background optics 433
8.1.1Polarizedlight 434
8.1.2Doublerefraction 437
8.1.3Theelectro-opticeffect 440
8.1.4Non-linearoptics 445
8.1.5Transparentceramics 448
8.2 Lanthanum-substituted leadzirconatetitanate 449
8.2.1Structureandfabrication 449
8.2.2Measurementofelectro-opticproperties 451
8.2.3Electro-opticcharacteristics 454
8.3 Applications 459
8.3.1Flashgoggles 459
8.3.2Colourfilter 460
8.3.3Display 460
8.3.4Imagestorage 461
8.3.5PLZTfilms 463
8.4 Opticalnon-linearity in glass andglass-ceramics 464
Problems 466
Bibliography 468
CONTENTS ix
9: Magnetic Ceramics 469
9.1 Magneticceramics: basic concepts 470
9.1.1Originsofmagnetisminmaterials 470
9.1.2Magnetizationinmatterfromthemacroscopicviewpoint 472
9.1.3Shapeanisotrophy:demagnetisation 473
9.1.4Magneticmaterialsinalternatingfields 475
9.1.5Classificationofmagneticmaterials 477
9.1.6Theparamagneticeffectandspontaneousmagnetization 479
9.1.7Magnetocrystallineanisotropy 481
9.1.8Magnetostriction 482
9.1.9Weissdomains 482
9.1.10Magnetizationinamultidomaincrystal 484
9.2 Model ferrites 486
9.2.1Spinelferrites:modelNiOFeO 486
2 3
9.2.2Hexaferrites:modelBaFe O 489
12 19
9.2.3Garnets:modelYFeO (YIG) 490
3 5 12
9.3 Propertiesinfluencing magnetic behaviour 492
9.3.1Softferrites 492
9.3.2Hardferrites 505
9.3.3Summaryofproperties 511
9.3.4Microwaveferrites 511
9.4 Preparation offerrites 517
9.4.1Rawmaterials 518
9.4.2Mixing,calciningandmilling 518
9.4.3Sintering 519
9.4.4Single-crystalferrites 520
9.4.5Magnetswithorientedmicrostructures 520
9.4.6Finishing 521
9.5 Applications 523
9.5.1Inductorsandtransformersforsmall-signalapplications 523
9.5.2Transformersforpowerapplications 529
9.5.3Antennas 530
9.5.4Informationstorageandopticalsignalprocessing 532
9.5.5Microwavedevices 535
9.5.6Permanentmagnets 541
Problems 543
Bibliography 545
Index 547