简介:BSTOdielectricceramicwaspreparedfromSrTiO3andBaTiO3powderssynthesizedbyhydrothermalmethod,aswellasfromBa0.6Sr0.4TiO3powdersynthesizedbyconventionalsolid-statereaction.Theformercanbesinteredatarelativelylowtemperatureof1120℃.CharacterizationbySEMshowedthatthegrainshapesofbothceramicsarecubical,thoughthegrainsizeoftheformerismuchsmaller.Dielectricconstantsmeasuredat20℃wereshowntovarywithfrequencyintherangefrom1kHzto2MHzanddcbiasfield,andfurtherthatthedielectriclossoftheformertobelessthan2×10-3inthefrequencyrangeof20kHzto1MHz,muchsmallerthanthatofthelattersample.Fortheformer,temperaturedependenceofdielectricconstantismuchflatterandthereexistsanextendedphasetransitiondiffusioncoveringawidetemperaturerangeofCurietemperatureTc.Thesmallergrainsizeoftheformerdepressesthedcbiaselectricalfielddependenceofdielectricconstant.Thetunabilityis7%underabiasfieldof0.6kV/mmdc.
简介:Thedielectricpropertiesofceramicswithcompositionof(Sr1-xBix)TiO3+x/2(wherex=0.05~0.70)weremeasuredatfrequencyof1MHz.Theexperimentalresultsindicatethatthedielectricpropertiesof(Sr1-xBix)TiO3+x/2systemaregreatlyvariedwithanincreaseofthestoichiometricamountsofBi2O3.Therelativepermittivityofthesolidsolutionsishigh,andthedissipationfactorislow.Thepositronannihilationtechnique(PAT)wasadoptedtostudythedefectstructure.AnexplanationofthedielectricpropertiesofBi-dopedSrTiO3ceramicshasbeensuggestedintermsofelectron-compensationandvacancyordefect-compensationmechanismsandspace-chargepolarizationmechanism.
简介:采用溶胶-凝胶法制备了Mn离子摩尔掺杂比.32分别为0,2%,4%,6%,8%的Ba(Ti1-xMnx)O3铁电薄膜。研究发现:当x为6%时,漏电流和矫顽场均达到最小,与未掺杂时相比,漏电流降低了约3个量级,矫顽场电场强度降低了约60%,P—E回线的矩形度增加。实验结果表明:通过适量掺杂Mn离子,可以改善BaTiO3铁电薄膜电学性能,提高铁电薄膜的极化,降低薄膜的漏电流。
简介:ThepiezoelectriccompositescontaininghighlyorientedBaTiO3whiskersasactivephaseandPVDFasmatrixhavebeenpreparedbymicro-holeextrusionandorientationincarriedfibers.ThemorphologyoforientedBaTiO3whiskersandmicrostructureofthecompositeswereobservedbySEM.Asforitselectromechanicalproperties,itisfoundthatthedielectricconstant,piezoelectricconstantandremnantofpolarizationintheBaTiO3whisker-PVDFcompositeareconsiderablyhigherthanthatintheBaTiO3powders-PVDFcomposite,whilethelossfactorsfollowtheoppositetrend.FortheBaTiO3whisker-PVDFcomposite,thevaluesofε,d33andPrparalleltothewhiskerorientation(normalspecimen)aremuchhigherthanthatperpendiculartothewhiskerorientation(parallelspecimen).Thesignificanteffectsoftheconnectivepassagesofactivephaseonelectromechanicalpropertiesofthepiezoelectriccompositeshasalsobeeninvestigated.
简介:BaTiO3/PVDFnanocompositeswerepreparedviain-situgrowthofnanosizedBaTiO3particlesinPVDFmatrixbyusingthesolgelmethod.ThepresentelementsofBaTiO3/PVDFnanocompositeswereana-lyzedbyanelectronprobeX-raymicroanalyser.NanosizedBaTiO3growninthecompositefilmswascharacterizedbyanX-raydiffractometerandatransmissionelectronmicroscope,andthedielectricpropertiesofthecompositefilmsweremeasured.ThedistributionofBaTiO3nanoparticlesin-situgrowninthePVDFmatrixwasexaminedus-ingascanningelectronmicroscope.
简介:为了开发新型高阻尼金属基复合材料,以高温烧结后的大晶粒钛酸钡(BaTiO3)陶瓷作为增强体,通过粉末冶金和热挤压方法制备钛酸钡颗粒增强铝基复合材料,并研究其阻尼特性和力学特性。动态力学分析结果表明,大晶粒钛酸钡陶瓷本身具有很好的阻尼性能,阻尼值可达0.12。但在纯铝基体中加入质量分数为10%BaTiO3制备的BaTiO3/Al复合材料的室温阻尼性能和铝基体相比并无明显改善,而450K以上的阻尼性能由于界面附近的位错运动而大幅度提高。钛酸钡增强体的本征阻尼性能未能充分发挥的原因在于钛酸钡颗粒与铝基体之间的界面结合不良,导致钛酸钡颗粒内部的能量耗散机制无法触动。复合材料的拉伸性能比相应纯铝基体的提高了42%,这意味通过改善界面结合和加入高含量的碳酸钡阻尼增强颗粒,有望获得高强度高阻尼金属基复合材料。
简介:采用溶胶-凝胶法制备了不同Zn含量掺杂的SrTiO3光催化剂(Zn-SrTiO3),通过X射线衍射(XRD)、扫描电子镜显微(SEM)和荧光光谱(PL)对其进行了表征,用亚甲基蓝(MB)光催化降解实验评价了其光催化活性。结果表明,SrTiO3经Zn掺杂后仍然保持了钙钛矿结构,Zn2+进入SrTiO3晶格对Sr2+进行了替位掺杂,导致晶格畸变;热处理温度升高,样品发生热团聚;适量的Zn掺杂,能有效降低光生电子和空穴的复合几率,提高SrTiO3的光催化活性;当掺杂量n(Zn):n(Sr)=1.5:100,热处理温度900℃时制备的样品光催化活性达95.5%,明显优于同等条件下纯SrTiO3活性58.5%,样品具有较高的光催化活性和良好的稳定性。