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1、Electronic Ceramics and Their ApplicationsX.M. Chen (陈湘明)Department of Materials Science & Engineering, Zhejiang University, Hangzhou 310027Tel: 87952112; E-mail: Web: http:/ 1Brief Introduction of X.M. ChenuWasborninHunan1959uB.S.Dept.Mater.Sci.&Eng.,CentralSouthUniversityin1981uPhDDept.Mater.Sci.&
2、Metallurgy,TheUniversityofTokyoin1991uResearchScientistatYokohamaR&DLabs.,FurukawaElectricCo.Ltd.(Japan),1991-1994uAssociateProfessor,Dept.Mater.Sci.Eng.,ZhejiangUniv.1994-1996uProfessor,Dept.Mater.Sci.Eng.,ZhejiangUniv.,Since1996uDistinguishedYoungScientistFoundationofNSFCin2000uProfessorof“Changji
3、angScholarProgram”2002uMember of International Advisory Board of MMA2000, MMA2002,MMA2006uChairman,MMA-2004(Inuyama,Japan)&MMA-2008(Hangzhou,China)uMemberofExecutiveBoard,AsianElectroceramicsAssociation(AECA).uAuthoredorco-authoredmorethan140papersinpier-reviewedinternationaljournalsu2Research Activ
4、ities in X.M. Chens Groupu微波介质陶瓷及其应用(Microwavedielectricceramicsandtheirapplications)u中介电常数微波介质陶瓷新体系u低介电常数微波介质陶瓷新体系u叠层介质谐振器u可调谐介电薄膜u铁电与介电新材料(Ferroelectricanddielectricnewmaterials)u巨介电常数材料(Giantdielectricconstantmaterials)u非铅铁电与弛豫铁电陶瓷(Pb-freeferroelectricandrelaxorferroelectricceramics)u微图案铁电薄膜(Micr
5、o-patternedferroelectricthinfilms)u复相与多功能耦合陶瓷(Compositeandmultifunctionalceramics)u磁电复相陶瓷 (Magetoelectriccompositeceramics)u多铁性材料 (Multiferroicmaterials)u磁性电介质(Magneticdielectrics)34功能陶瓷的基本概念与结构陶瓷相对应的概念，主要指具备特定的电、磁、声、光、热等物理性能的陶瓷材料；电子陶瓷是功能陶瓷的主体；电子陶瓷：介电陶瓷(绝缘陶瓷)、铁电陶瓷、反铁电陶瓷、压电陶瓷、热释电陶瓷、半导体陶瓷、电光陶瓷、磁性陶瓷等在电
6、子、通讯、军事、以及家电技术中有着广泛的应用。56789功能陶瓷的学科关系学科基础：固体物理、固体化学、电磁学、材料科学基础相关学科：电子、通讯、仪器仪表等无机非金属材料功能材料功能陶瓷10功能陶瓷现代电子技术的三大物质基础之一半导体材料电介质材料(功能陶瓷)光电子材料微电子学固体电子学光电子学电子材料111213Primary ContentsElements of Dielectrics (电介质) and CeramicInsulatorsFerroelectric(铁电),RelaxorFerroelectric(驰豫铁电), Antiferroelectric (反铁电) Ceram
7、ics andCeramicCapacitors(电容器)MicrowaveDielectricCeramics(微波介质陶瓷)Piezoelectric(压电)andOpto-electricCeramicsCeramicSensorsZnOVaristors(变阻器)ConductingCeramics14Chapter 1 Elements of Dielectrics and Ceramic InsulatorsI. Elements of Dielectrics15物质按导电性能的分类载流子长程运动与位移传导、宏观电流n导体：金属、部分非金属n半导体：部分非金属单质与化合物n绝缘体
8、（无载流子长程运动与位移）：大部分非金属单质与化合物载流子短程运动与位移极化(Polarization)n电介质（绝缘体+半导体；通常为绝缘体）16电介质的基本物理概念-极化极化-正负电荷中心偏移偶极矩(dipolemoment)p=Qdx(1.1)极化强度PP=dp/dV=Njmj(1.2)(Nj=numberofdipolesoftypej;mj=averagedipolemoment)mj=ajE(1.3)aj-polarizabilityofaveragedipolemoment;E-localelectricfieldP=sp(surfacechargedensity)(1.4) 1
9、7极化机理at= as+ao+ai+ae (1.5) ae-Electronic(Atomic)Polarization;ai-IonicPolarization;ao-Orientation(Dipolar)Polarization;as-SpaceChargeorDiffusionalPolarization181920电位移D、电场强度E与极化强度P的关系Forcasea):E=s/e0 (1.6)s-surfacechargedensityForcaseb):E=(sT-sP)/e0(1.7)sTtotalsurfacechargedensity;sPpolarazationcharg
10、edensitySinceP=sPandsT=D(electricdisplacement)e0E=P-D (1.8) D= e0E+P (1.9) Ifthedielectricislinear,P=cee0E,sothatD= e0E+cee0E=(1+ce)e0E (1.10)where,ceiselectricsusceptibility,atensorofthesecondrank21介电常数(Dielectric Constant)SinceD=sT,QT/A=(1+ce)e0U/h(1.11)QT=(1+ce)e0UA/h(1.12)C=QT/U=(1+ce)e0A/h(1.13
11、)Sincevacuumhaszerosusceptibility,C0=e0A/h(1.14)Ifthespacebetweentheplatesisfilledwithadielectricofsusceptibilityce,thecapacitanceisincreasedbyafactor1+ce.Permittivityeofthedielectricisdefinedbye=e0(1+ce)(1.15)Dielectricconstant(relativepermittivity)er=e/e0=1+ce(1.16)22Anindividualatomorioninadielec
12、tricisnotsubjecteddirectlytoanappliedfieldbuttoalocalfield.TheinternalmacroscopicfieldEmistheresultantofappliedexternalfieldEaanddepolarizingfieldEdp,i.e.Ea-Edp.Itisassumedthatthesolidcanberegardedascomprisingidentifiablepolarizableentitiesontheatomicscale.ThelocalfieldEL(orLorentzfield)differfromEm
13、sincethelatterisarrivedatbyconsideringthedielectricasacontinuum.EL=Em+Ep+Ed(1.17)where,Ep-thecontributionfromthechargesatthesurfaceofthesphericalcavity(imagingforthemomentthatthesphereofmaterialisremoved);Ed-duetothedipoleswithintheboundary.Applied External Field, Internal Macroscopic Field & Local
14、(Lorentz) Field23Clausius-Mosotti EquationEpcanbeshowntobeP/3e0,andEd=0forcertaincrystalsofhighsymmetryandglasses.Sothat,EL=Em+P/3e0=Ea-Edp+P/3e0(1.18)Inmoregeneralcase,itisassumedthatEL=Em+gP(1.19)inwhichg isthe“internalfieldconstant”Thedipolemomentpinducedintheentitycanbenowwrittenasp=a EL (1.20)I
15、fitisassumedthatallentitiesareofthesametypeandhaveadensityN,then P=Np=Na(Em+gP) (1.21) Or P/e0Em=ce=Na/e0/(1-Nag) (1.22)Intheparticularcaseforwhichg=1/3eo,wehavetheClausius-MosottiEquation(er-1)/(er+2)=Na/3e0(1.23)24介电损耗(Dielectric Loss)25介电损耗(Dielectric Loss)对于理想电介质，极化能适时响应外电场变化，电位移与电场的相位相同(电流超前p/2
16、) 不产生能量损耗；而对于实际电介质，极化不能适时响应外电场变化(滞后于电场d-损耗角),而出现介电弛豫介电损耗。介电损耗的数学描述 E=E0exp(iwt)(1.24)D=D0expi(wt-d)(1.25)利用D=k*E，得k*=ksexp(-id)=ks(cond-isind) (1.26) 其中，ks- 静态介电常数(=D0/E0)26介电损耗(Dielectric Loss)利用复介电常数的概念k*=k-ik”=e*/e0=(e-ie”)/e0(1.27) k=kscosd (1.28)k”=kssind (1.29)tand=k”/k=e”/e(1.30)tand即为介电损耗物理意
17、义物理意义 极化过程中消耗的能量与储存的能量的比值电介质的品质因数：Q=1/tand27Resonance Effects Inthe case of atomic and ionic polarization,theelectronsandionsbehave,toafirstapproximation,asthoughboundtoequilibriumpositionsbylinearspringssothattherestoringforceisproportionaltodisplacement,adampingfactorgisincludedintheequationofmoti
18、on.(1.31)Solving(1.31)andignoringthetransienttermyields(1.32)Sinceex(t)istheinduceddipolemomentperatom,thecomplexpolarizationP*isgivenby(1.33)28Resonance EffectsAnd(1.34)Sothat(1.35)Byequatingrealandimaginaryparts(1.36)(1.37)Theabovethecontributionsofionicandelectronicpolarization,whicharesensiblyin
19、dependentoftemperature,theresonancecurvesarealso.29Variationinandwithfrequencyclosetoaresonancefrequencyw0.30RelaxationEffectsIn contrast with the electronic and ionic polarization processes, the diffusionalpolarizationanddepolarizationprocessesarerelativelyslowandstronglytemperaturedependent.The di
20、ffusional polarization Pd approaches its final static value Pds according thefollowingequation(1.38)where,tisarelaxationtime.Integrating(1.38)withinitialconditionPd=0whent=0gives(1.39)Toaccountforalternatingappliedfield,Eq.(1.38)shouldbemodifiedto(1.40)where,ersisthelowfrequencydielectricconstant.31
21、RelaxationEffects&DebyeEquationsEquation(1.40)canbeintegratedtogive(1.41)ByneglectingthetransientCexp(-t/t),wecanget(1.42)TheDebyeEquationsareobtainedbyseparatingtherealandimaginarypartsofEq.(1.42)(1.43)(1.44)Therelaxationfrequencyisw=1/t323334Dielectric DispersionWithincreasingfrequency,dielectricc
22、onstantgenerallydecrease,andsomepeaksappearfordielectricloss.Originsofdielectricdispersion:Rrelaxationprocess(orientationandspacechargepolarization)Resonanceprocess(electronicandionicpolarization)Availablefrequenciesforvariouspolarizationmechanisms:Spacechargepolarization:102HzOrientationpolarizatio
23、n:106HzIonicpolarization:1013HzElectronicpolarization:1016Hz35Cole-Cole DistributionsColeandCole(1942)modifiedequation(1.42)byincludinganexponenta (1.45)Thedistributionisobtainedbyplottinger”asafunctionofer,yieldingwhatistermedtheCole-Coledistribution.Usingthecircuitparameters,weobtain(1.46)Or(1.47)
24、36k” or e”k or eC1/e0(C1+C2)/e0w0RC2=1IndicateshighlossesRCcircuitCole-ColeplotCole-Cole Plot and the RC Circuit37Physical Meaning of Cole-Cole PlotTheCole-Coleplotofamaterialisameasureofthevariousrelaxationtimesforaspecificdielectricmaterial.Averynarrowdistributionofrelaxationtimesperfectdielectric
25、.Thisindicatesthatonlyoneprimarymechanismexistsforthepolarizationwithinthematerial;Atailinthedistributionindicatesalargedistributionofrelaxationtime;Alargerangeofrelaxationtimescanindicatemultiplepolarizationmechanismsbutalsolossesduetoconduction.AperfectorlowlossdielectricwouldhaveaCole-Coleplottha
26、tisnearlyasemicircle;Apoororhighlossdielectricwouldhaveanon-boundedincreasinger”withincreasinger.38Dielectric Strength (介电强度)Dielectric breakdown( (介电击穿介电击穿) ):Alldielectricswhenplacedinanelectricfieldwilllosetheirinsulatingpropertiesifthe field exceeds a certain critical value.This phenomenon is ca
27、lled dielectricbreakdown.Dielectric strength1.48)Dielectric breakdown mechanismsIntrinsicbreakdownThermalbreakdownInonizationbreakdownElectrochemicalbreakdown39Factors Affecting Dielectric StrengthComposition:amorphousorcrystallinenature,presenceofmobileions;Microstructural features: porosity, grain
28、 size,cracks,flaws,secondaryphases;Measurement parameters:electrodeconfiguration,specimenthickness,temperature,time,frequency,humidityandheattransferconditions.40Chapter 1 Elements of Dielectrics and Ceramic InsulatorsII. Ceramic Insulators41IntoductionFunctionofinsulatorinelectriccircuits:Physicals
29、eparationofconductorsandtheregulationorpreventionofcurrentflowbetweenthem;Ancillarybutimportantotherfunctionsaretoprovidemechanicalsupport,heatdissipationandenvironmentalprotectionfortheconductorsAdvantagesofceramicinsulators:Materialstypeusedasinsulators:lineardielectricsTypicalelementsofceramicins
30、ulator:ceramicsubstrates,ceramicpackages42Property Requirements to Ceramic InsulatorsDielectricconstant;Dielectricloss;Dielectricstrength;Resistivity(1.49)Thermalconductivity;Thermalexpansioncoefficient;Mechanicalproperties.43Property Criteria for Good Ceramic InsulatorsDielectricconstant:notgreater
31、than30;Electricresistivity:notlessthan1012W-cm;Dielectricloss(dissipationfactor):notlargerthan0.001;Dielectricstrength:notlessthan5.0kV/mmDielectriclossfactor:notlargerthan0.0344Propertiesat1MHz(roomtemperature)MaterialTandDielectricconstantLossfactorDielectricstrengthResistivityat25oC(cm)Porcelain(
32、R2OAl2O3SiO2)0.008-0.0205.0-6.50.04-0.136.1-13.01014Zircon(ZrO2SiO2)0.0018.0-9.60.008-0.00966.3-11.51014Steatite(MgOSiO2)0.008-0.00356.00.005-0.027.9-13.81014Forsterite(2MgOSiO2)0.0005-0.0015.8-6.70.003-0.0077.9-11.91017Cordierite(2MgO2Al2O35SiO2)0.003-0.0054.1-5.30.012-0.0255.5-9.11017Alumina(Al2O3
33、90-99.9%)0.0003-0.0028.8-10.10.03-0.029.9-15.81016Spinel(MgOAl2O3)0.00047.50.00311.91016Mullite(3Al2O32SiO2)0.0056.2-6.80.03-0.0347.81014Magnesia(MgO)0.00018.90.00898.5-11.01014Beryllia(BeO96-99%)0.0001-0.0016.00.006-0.069.5-13.81016Zirconia(ZrO2)0.0112.00.125.0109Table1.1DielectricpropertiesofCeram
34、icInsulators 45Table1.1DielectricpropertiesofCeramicInsulatorsMaterialTandDielectricconstantLossfactorDielectricstrengthResistivityat25oC(cm)Thoria(ThO2)0.000313.50.0045.31010Hafnia(HfO2)0.01120.12108Ceria(CeO2)0.0007150.011109Spodumene(Li2OAl2O3SiO2)0.0056.5-7.50.03-0.041011Boronnitride(BN)0.0014.2
35、0.00435.6-55.41014Siliconnitride(Si3N4)0.00016.10.000615.8-19.81013-14Pyroceram0.0017-0.0135.5-6.30.01-0.079.9-11.91012Glass-bondedmica0.0015-0.0036.4-9.20.011-0.02310.6-23.71014Mica0.00025.4-8.70.001-0.00239.5-79.11016Glass(Na2OCaOSiO2)0.0005-0.014.0-8.00.002-0.087.8-13.21012Quartz(SiO2)0.00033.8-5
36、.40.001515-25.01014-18Pb-Alsilicate0.0018.2-150.008-0.0158.9-16.01013AluminumNitride(AlN)0.00018.8-8.90.001151013Silicon11.946Table1.2ThermomechanicalPropertiesofCeramicInsulators MaterialSpecificgravityThermalconductivityat25oC(cal/sec-oC-cm)Thermalcoefficientofexpansion25-300oC(10-6/oC)Tensilestre
37、ngth(Mpa)MORTransvstrength(Mpa)Compressstrength(Mpa)ThernalshockresistancePorcelain(R2OAl2O3SiO2)2.40.0066.04883352FairZircon(ZrO2SiO2)3.70.0124.3-4.896172524GoodSteatite(MgOSiO2)2.80.0066.9-7.8100125650ModerateForsterite(2MgOSiO2)2.80.006-0.011076140550PoorCordierite(2MgO2Al2O35SiO2)2.2-2.90.005-0.
38、0072.2-2.465105400ExcellentAlumina(Al2O390-99.9%)3.85-3.90.06-0.078.02604453400GoodSpinel(MgOAl2O3)2.80.0186.6951031710FairMullite(3Al2O32SiO2)2.6-3.20.014.3-5.0901501200FairMagnesia(MgO)3.3-3.50.04-0.00910-1390138950FairBeryllia(BeO96-99%)2.8-2.950.4-0.77-91202481600GoodZirconia(ZrO2)5.43-5.560.02-
39、0.054.3-8.3148186940Poor47Table1.2ThermomechanicalPropertiesofCeramicInsulatorsMaterialSpecificgravityThermalconductivityat25oC(cal/sec-oC-cm)Thermalcoefficientofexpansion25-300oC(10-6/oC)Tensilestrength(Mpa)MORTransvstrength(Mpa)Compressstrength(Mpa)ThernalshockresistanceThoria(ThO2)9.70.0335.3-9.0
40、1151311524PoorHafnia(HfO2)9.00.0046.5901101386PoorCeria(CeO2)7.00.02910.0881101386PoorSpodumene(Li2OAl2O3SiO2)2.40.0122.03055900GoodBoronnitride(BN)2.2-2.30.04-0.074.52552250GoodSiliconnitride(Si3N4)3.2-3.40.03-0.072.5-3.54106102000ExcellentPyroceram2.4-2.60.004-0.0090.2-0.464248GoodGlass-bondedmica
41、2.6-3.80.001210-14.569117214FairMica2.6-3.80.0008-0.00218-27221Glass(Na2OCaOSiO2)2.0-8.00.002-0.0040.5-1.034120697FairQuartz(SiO2)2.20.0030.3-0.4551130ExcellentAluminumNitride(AlN)2.61-2.930.048-0.0724.03-6.09441Sliconcarbide(SiC)3.1-3.20.012.6-4.385490138048Materials Systems for Ceramic Insulatorsn
42、GlassesnPorcelainsnSteatite (滑 石 ,MgO.SiO2), Forstrite(镁 橄 榄 石 ,2MgO.SiO2),Cordierite(堇青石,2MgO.2Al2O3.5SiO2),Spinel(尖晶石,MgO.Al2O3),Mullite(莫来石,3Al2O3.2SiO2),nSingleoxideandnitridesceramicsnAlumina(Al2O3),Magnesia(MgO),Boronnitride(BN),Aluminumnitride(AlN),Siliconnitride(Si3N4)49Property Criteria for
43、 Good Ceramic InsulatorsDielectricconstant:notgreaterthan30;Electricresistivity:notlessthan1012W-cm;Dielectricloss(dissipationfactor):notlargerthan0.001;Dielectricstrength:notlessthan5.0kV/mmDielectriclossfactor:notlargerthan0.0350Property Target for Ceramic SubstratesLowdielectricconstant:e7Lowdielectricloss:tand4x10-4Highresistivity:r1012-1014W.cmHighthermalconductivity;CoefficientofthermalexpansionclosetothatofSi.51作业就下列问题之一进行专题调研、在独自撰写小论文的基础上，自愿组合成小组(10-11人)、共同准备PPT文件，并推举代表演讲(15分钟)。*1)绝缘陶瓷的材料体系2)陶瓷基板的研究现状与发展趋势*第2周准备论文与讲稿、9/21演讲52
