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论文题目：NBT基无铅压电陶瓷的制备与电性能研究专业：材料学硕士生：宋瑞雪(签名)指导教师：杜慧玲(签名)摘要压电陶瓷是一种可实现机械能与电能相互转换的功能材料。传统的压电陶瓷在制备过程中存在着铅的挥发，不仅使陶瓷的化学计量比偏高，还会对环境造成污染。Na1/2Ba1/2TiO3(简称NBT)具有很强的铁电性，是一种很有希望的无铅压电材料。但纯NBT具有较高的矫顽场和电导率，极化十分困难，压电性能难于充分表现出来，通过掺杂取代可降低其矫顽场。本论文以K+、Ba2+、Li+离子对NBT基陶瓷进行A位取代，采用固相合成法，制备出NBT基陶瓷样品，系统研究了材料的制备工艺、结构、介电性能和压电性能，分析了NBT基陶瓷的压电性能与组成、结构之间的相关性，并结合实验结果探讨了NBT基陶瓷的铁电本质及其对材料压电性能的影响。XRD分析表明，随着K+、Ba2+、Li+离子取代量的增加，样品的晶体结构逐渐由三方相向四方相转变，在x=0.03时，材料体系存在三方、四方相共存的准同型相界。SEM分析表明，K+、Ba2+、Li+离子的掺入抑制了晶粒的长大，使晶粒的尺寸变小。测试了各组成点样品的压电性能，结果表明，与PZT基含铅压电陶瓷相似，材料在准同型相界组成范围内压电性能昀佳d33=150pC/N。测试了样品的电滞回线，发现K+、Ba2+、Li+离子的掺入有效降低了NBT基陶瓷的剩余极化强度和矫顽场，样品的矫顽场降至Ec=2.4kV/mm.研究了样品在不同频率下(0.1,1,10,100kHz,1MHz)，从室温到500℃的介电性能与温度的变化关系。系列样品的介电温谱显示在所测温度范围内存在两个介电反常峰，分别对应于陶瓷材料的铁电-反铁电-顺电相变，同时发现该系列样品显示出弛豫铁电体特性，并用成分起伏理论解释了这种弛豫弥散相变。研究了NBT基陶瓷的铁电性。研究结果表明，NBT基陶瓷铁电性能与压电性能的变化规律存在明显的对应关系。剩余极化强度Pr和矫顽场Ec都是影响材料压电性能的重要因素。一方面，高的矫顽场Ec使材料在极化过程中铁电畴无法充分转向，不利于提高压电性能；另一方面，高的剩余极化强度Pr使材料铁电性的增强，有利于提高压电性能。NBT基陶瓷的压电性能依赖于剩余极化强度Pr和矫顽场Ec的共同作用。以NBT-KBT-BT为基础掺杂一定量的CeO2和MnO2均不会改变材料的三方、四方共存结构，但掺杂后晶胞体积有不同程度的增加，掺杂后的陶瓷在一定掺杂量范围内能提高陶瓷的压电常数和介电损耗，降低了平面机电耦合系数，均具有“软硬双性”添加物的作用。关键词：钛酸铋钠；钛酸铋钾；钛酸钡；无铅压电陶瓷；钙钛矿；弛豫铁电体研究类型：应用研究Subject：StudyonPreparationandElectricPropertiesofNBT-basedLead-freePiezoelectricCeramicsSpecialty：MaterialScienceName：SONGRuixue（Signature）Instructor：DUHuiling（Signature）ABSTRACTPiezoelectricceramicisafunctionmaterialwhichcanexchangeenergybetweenmechanicandelectricity.TraditionalpiezoelectricceramicsgiveoffPbVaporinthepreparation.TheevaporationofPbcausednotonlydeviationofthecompositionofceramicbutalsothepollutiontoenvironment.NBThasstrongFerroelectricperformance;itissupposedtobeahopefullead-freepiezoelectricceramic.ButitisdifficulttopolenetNBTbecauseofthehighcoercivefieldandconductivity,sothepiezoelectricpropertiescannotbeexploitedcompletely.Thecoercivefieldcanbedecreasedbydopand.Inthispaper,theNBT-basedceramicswerepreparesinsolidsyntheticway.TheK+、Ba2+、Li+substitutedfortheinstrinsiccationsattheAsitesofpreovskite,andthesynthesisandpreparation,structuralcharacteristics,dielectricpropertiesandpiezoelectricpropertiesofNBT-basedceramicshavebeeninvestigated.Theinfluenceofthecompositionandstructureonthepiezoelectricpropertieshasbeenstudied.Therelationbetweentheferroelectricnatureandpiezoelectricpropertieshasbeenestablishedintermsofexperimentalresults.XRDresultindicatethatthefabrictransitedformrhombohedraltotetragonalgraduallywiththesubstitutionoftheK+,Ba2+,Li+Morphotropicphaseboundaries{MPB}oftheceramicexistinthecompositionatx=0.03.SEMresultsshowthatthegrowthofthecrystallinegrainwasrestrainedandthedimensionofitturnedlittler.Thepropertiesofallsampleswereinvestigated;itisthesametothePZTceramicssamplesinthecompositionrangeofMPBexhibitedbestpiezoelectricperformanced33=150pC/N.Thehysteresisloopsweredetected,itisfoundthattheremnantpolarizationandtheconceivefieldoftheceramicsdeceasedwiththedopeofK+,Ba2+,Li+.InthecompositionrangeofMPB,theconceivefieldexhibitthelowestvalueEc=2.4kV/mm.Thedielectricpropertiesofsamplesfromroomtemperatureto500℃atdifferentfrequencies(0.1,1,10,100kHz,1MHz)werestudied.Twodielectricconstantabnormalpeaksexists，whichcorrespondingtothephasetransitionofferroelectrictoantiferroelectricandantiferroelectrictoparaelectricphase.Itwasalsofoundthatinthecompositionsthuspreparedwereallrelaxorferroelectric.Andthecausesofdiffusephasetransitionwereinterpretedbythetheoryofheterophasefluctuation.TheferroelectricpropertiesofNBT-basedceramicswereinvestigated.TheresultsconfirmanessentialrelationbetweentheferroelectricnatureandpiezoelectricpropertiesforNBT-basedceramics.Boththeremnantpolarization(Pr)andcoercivefield(Ec)affectthepiezoelectricpropertiesofthespecimens.Thiscanbequalitativelyinterpretedasfollows.Ononehand,ahighcoercivefieldisdisadvantageoustothesufficientreorientationofferroelectricdomainsduringelectricalpoling,generatinganegativeeffectonpiezoelectricproperties.Ontheotherhand,ahighremnantpolarizationindicatesastrongferroelectricity,whichenhancespiezoelectricproperties.Therefore,thepiezoelectricpropertiesofthespecimensaredependentonthedualcontributionofremnantpolarizationandcoercivefield.CeO2andMnO2dopedNBT-KBT-BTceramicscannottransformthecrystallinestructure,butcanenlargetheunitvolume.Thepiezoelectricconstrictconstant,dielectriclosswereenhancedbutelectro-mechanicalcouplingfactorwasdecreasedbydopingappropriateamountofdopantofCeO2andMnO2.ThismeansthatthedopantofCeO2andMnO2have“softandharddoublepropertiesdopant”effect.Keywords：Sodium-bismuthtitanatePotassium-bismuthtitanateBariumtitanateLead-freepiezoceramicsPerovskiteRelaxorferroelectricThesis：ApplicationResearch主要符号表主要符号表d33——压电系数ε——介电系数tanδ——介电损耗Qm——机械品质因数Kp——机电耦合系数N——频率常数Pr——剩余极化强度EC——矫顽场强TC——居里温度d%——线收缩率ρ——体积密度目录目录1绪论........................................................................................................................................11.1压电陶瓷材料概述..........................................................................................................11.1.1压电陶瓷的发展历史.........................................................................