简介:ThetransportpropertiesintheLa2/3(Ca1-xSrx)1/3MnO3(x=0,1/3,2/3)filmspreparedusingtheRFmagnetronsputteringmethodwereinvestigated.TheeffectoftheCa,Srdouble-dopingattheApositionintheLa2/3A1/3MnO3onthestructureofthetargetsandtransportofthefilmshasbeenstudied.Withtheincreaseofx,thestructuresofthetargetstransformfromtherhombohedralphasetothecubicphase;themetal-insulatorphasetransitiontemperature(Tp)ofthefilmsincreases;andthecorrespondingpeakresistivitydecreases.Allthephenomenacanbequalitativelyexplainedbythelatticeeffect.
简介:Intrinsiccarrierconcentration(ni)isoneofthemostimportantphysicalparametersforunderstandingthephysicsofstrainedSiandSi1-xGexmaterialsaswellasforevaluatingtheelectricalpropertiesofSi-basedstraineddevices.Uptonow,thereportonquantitativeresultsofintrinsiccarrierconcentrationinstrainedSiandSi1-xGexmaterialshasbeenstilllacking.Inthispaper,byanalyzingthebandstructureofstrainedSiandSi1-xGexmaterials,boththeeffectivedensitiesofthestatenearthetopofvalencebandandthebottomofconductionband(NcandNv)at218,330and393KandtheintrinsiccarrierconcentrationrelatedtoGefraction(x)at300KweresystematicallystudiedwithintheframeworkofKPtheoryandsemiconductorphysics.ItisfoundthattheintrinsiccarrierconcentrationinstrainedSi(001)andSi1-xGex(001)and(101)materialsat300KincreasessignificantlywithincreasingGefraction(x),whichprovidesvaluablereferencestounderstandtheSibasedstraineddevicephysicsanddesign.
简介:Themetalorganicvaporphaseepitaxy(MOVPE)growthofindiumgalliumnitride(InGaN)hasbeendiscussedindetailtowardsthefabricationofsolarcell.TheInGaNfilmwithIncontentsupto0.4aresuccessfullygrownbycontrollingthefundamentalgrowthparameterssuchastheprecursorgasflowrates,temperatureetc.TheformationofmetallicInoriginatesfromthehighervalue(0.74)oftrimethylindium/(trimethylindium+triethylgallium)(TMI/(TMI+TEG))molarratiowithlow(4100)V/Ⅲweightmolarratiowhilethelowervalue(0.2)ofTMI/(TMI+TEG)causesthephaseseparation.Itisalsonecessarytocontrolthegrowthrateandepitaxialfilmthicknesstosuppressthephaseseparationinthematerial.ThecrystallinequalityofgrownfilmsisstudiedanditisfoundtobemarkedlydeterioratedwithincreasingIncontent.ThelatticeparametersaswellasthethermalexpansioncoefficientmismatchbetweenGaNtemplateandInGaNepi-layerareprimarilyconsideredasthereasonstodeterioratethefilmqualityforhigherIncontent.ByusingIn0.16Ga0.84Nfilms,ann+-phomo-junctionstructureisfabricatedon0.65mmGaNtemplate.Forsuchadevice,theresponsetothelightillumination(AM1.5)isobservedwithanop-ncircuitvoltageof1.4Vandtheshortcircuitcurrentdensityof0.25mA/cm2.Toimprovetheperformanceaswellasincreasesolarphotoncapturing,thedeviceisfurtherfabricatedonthickGaNtemplatewithhigherIncontent.TheIn0.25Ga0.75Nn+-pjunctionsolarcellisfoundbetterperformancewithanop-ncircuitvoltageof1.5Vandtheshortcircuitcurrentdensityof0.5mA/cm2.ThisistheInGaNp-nhomo-junctionsolarcellwiththehighestIncontenteverreportedbyMOVPE.
简介:Nd_2Zr_2O_7isbeingexploredasanalternatethermalbarriercoating(TBC)materialforoperatingabove1300°C,andgreatefforthasbeenmadetoenlargeitsthermalexpansioncoefficient(TEC)andimproveitstoughness.Inthisstudy,Sc_2O_3wasdopedtoNd_2Zr_2O_7.Thephasestructure,TECsandtoughnessof((Nd_(1-x)Scx))_2Zr_2_O7(x=0,0.025,0.05,0.075,0.1)compoundswereinvestigated.((Nd_(1-x)Scx))_2Zr_2_O7(x=0,0.025,0.05,0.075)exhibitedpyrochlorestructure,while((Nd_(0.9)Sc_(0.1)))_2Zr_2O_7consistedofpyrochloreandfluoritephases.WiththeincreaseoftheSc_2O_3content,theorderingdegreeofthepyrochloreinthecompoundsdecreased.In((Nd_(1-x)Scx))_2Zr_2O_7series,((Nd_(0.925)Sc_(0.075)))_2Zr_2O_7exhibitedthelargestTEC,whilethetoughnessofthecompoundsincreasedwithincreasingtheSc_2O_3content.Therelatedmechanismswerediscussedbasedonthecrystalstructureanalysis.ConsideringtheTECandtoughness,10mol%Sc_2O_3wassuggestedastheoptimaldopingcontentforNd_2Zr_2O_7ceramic.
简介:第三产生同步加速器X光象自然材料一样为许多设计材料的微结构描述提供一个崭新的机会。这篇文章为结构的材料的学习表明三种技术的用法:微分孔的X光检查显微镜学(DAXM),三维的X光检查衍射(第3DX),和散布的同时的宽angle/small角度X光检查(蜡/萨克斯风管)。DAXM能与高空间、尖的分辨率在多晶的材料测量3D谷物结构。在使变形的材料,streaked衍射山峰能被用来在单个谷物分析本地脱臼内容。比作DAXM,第3DX能大批印射谷物材料更快速在损坏空间分辨率的情况下。当材料在变丑下面时,发展微观结构,为学习是很有用的。蜡/萨克斯风管对与不同类的结构学习材料合适,例如猛抛加强的合金。蜡和萨克斯风管揭示的结构的信息能为更深的卓见被合为材料行为。这三种技术的未来开发和应用程序将也被讨论。
简介:AseriesofCd1-xZnxS/K2La2Ti3O10compositesweresynthesizedviaasimpleco-precipitationmethod.ThepreparedsampleswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),X-rayenergydispersivespectroscopy(EDX),ultraviolet-visiblediffusereflection(UV-Vis),X-rayphotoelectronspectroscopy(XPS)andphotoluminescence(PL)measurements.ThecompositestructuresconsistedofCd1-xZnxSnanoparticlesevenlydistributedonthesurfaceofK2La2Ti3O10.TheabsorptionedgeofK2La2Ti3O10shiftedtothevisiblelightregionuponintroductionoftheCd1-xZnxSnanoparticles.Thephotocatalyticactivitiesofthecatalystswereevaluatedbyhydrogenproductionundervisiblelightirradiation.ThepreparedCd0.8Zn0.2S(30wt%)/K2La2Ti3O10exhibitedhigherphotocatalyticactivity,evolving6.92mmol/gH2undervisiblelightirradiationfor3h.ThepromotedphotocatalyticactivityofthecompositeswasattributedtothesynergisticeffectbetweenCd1-xZnxSandK2La2Ti3O10,whichresultedinenhancedseparationofphotogeneratedelectronsandholes.
简介:Inordertostudythestresscorrosioncracking(SCC)ofX70pipelinesteelanditsweldjointinacidsoilenvironmentofsoutheastofChina,twosimulatingmethodswereusedhere.Theonewastoobtainthebadmicrostructuresinheataffectedzonebyannealingat1300°Cfor10minandaircoolingtoroomtemperature,theotherwastogetaseriesofsimulatingsolutionsoftheacidsoilenvironment.SCCsusceptibilitiesofX70pipelinesteelsbeforeandafterbeingnormalizedinthesimulatedsolutionswerestudiedbyslowstrainratetest(SSRT)andmicrostructuralobservationoffractureareas.Potentiodynamicpolarizationcurveswereusedtostudytheelectrochemicalbehaviourofdifferentmicrostructures.SCCdoesoccurtoboththeas-receivedmaterialandnormalizedmicrostructureafterheattreatmentasthepolarizationpotentialdecreased.Hydrogenembrittlement(HE)isindicatedoccurringtoalltestedmaterialsat-850mV(vsSCE)and-1200mV(vsSCE).TheSCCmechanismsaredifferentwithinvaryingpotentialrange.Anodicdissolutionisthekeycauseaspolarizationpotentialhigherthannullcurrentpotential,andHEwillplayamoreimportantroleaspolarizationpotentiallowerthanthenullcurrentpotential.
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简介:Thesystematiclaboratorystudiesontherolesofsulfate-reducingbacteria(SRB)inthestresscorrosioncracking(SCC)susceptibilityofX80steelsubjectedtocathodicpotentialhavebeenconductedinanearneutralpHsoilsolutionbyslowstrainratetests.ThecathodicpotentialandSRBincreaseindividuallytheSCCsusceptibilityofthesteelinthesoilsolution.ThepositiveroleoftheSRBactivitiesinSCCsusceptibilitydependsontheprolongationofpre-incubationtime,andtheSCCsusceptibilityofthesteelincreasesundermorenegativepotentials.What’smore,theappliedpotentialsandthepresenceofSRBworktogetherinpromotingtheSCCsusceptibilityofthesteel.But,thecombinedactionbecomeslimitedwithdecreasingcathodicpotentials.Therelationshipsbetweentheplasticitylossandthepermeablehydrogenconcentrationwereestablishedforthesteelinthesoilsolution,regardlessofunderopencircuitpotentialorcathodicpotentials,inboththesterileandSRBinoculatedconditions.Therelationshipsarepracticallysignificantfortheselectionofsafecathodicprotection(CP)potentialsinthepresenceofSRBinsoilenvironment.