简介:LayeredcathodematerialLiCo1/3Ni1/3Mn1/3O2wassynthesizedbyPechiniprocess,andinvestigatedusingX-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andgalvanostaticcharge/dischargecycling.Thesampleiswell-crystallizedandhasaphase-purea-NaFeO2structure.Theparticlesizesareuniform,anddistributedintherangeof20-200nm.TheinitialdischargecapacityoftheLi/LiCo1/3Ni1/3Mn1/3O2cellwasabout149mAh·g-1whenitwascycledatavoltagerangeof4.5-2.3Vwithaspecificcurrentof0.25mA.Theresultisbetterincomparisonwithsolid-statesolutionmethod.Thesyntheticprocedurewasdiscussed.Threemajorreactions:chelation,esterification,andpolymerizationsuccessivelyoccurred.
简介:EmployingLi2CO3,NiO,Co3O4,andMnCO3powdersasstartingmaterials,Li[Ni1/3Co1/3Mn1/3]O2wassynthesizedbysolid-statereactionmethod.Variousgrindingaidswereappliedduringmillinginordertooptimizethesynthesisprocess.Aftersuccessiveheattreatmentsat650and950℃,thepreparedpowderswerecharacterizedbyX-raydiffraction(XRD)analysis,scanningelectronmicroscopy,andtransmissionelectronmicroscopy.Thepowderspreparedbyaddingsalt(NaCl)asgrindingaidexhibitaclearR3mlayerstructure.ThepowdersbyothergrindingaidslikeheptaneshowsomeimpuritypeaksintheXRDpattern.Theformerpowdersshowauniformparticlesizedistributionoflessthan1μmaveragesizewhilethelattershowsawidedistributionrangingfrom1to10μm.EnergydispersiveX-ray(EDX)analysissshowthattheratioofNi,Co,andMncontentinthepowderisapproximately1/3,1/3,and1/3,respecively.TheEDXdataindicatenoincorporationofsodiumorchlorineintothepowders.Charge-dischargetestsgaveaninitialdischargecapacityof160mAh·g-1forthepowderswithNaCladditionwhile70mAh·g-1forthepowderswithheptane.
简介:晶体结构和加氢行为(La_(1-x)Mg_x)_3Al(x=0.1,0.2,0.3,和0.4)合金被调查。这被发现有x=的合金0.1La和第0.2consi(Mg,艾尔),La,和一个新奇阶段。新奇阶段作为La_2Al被决定。当Mg满足增加,La_2Al的数量减少,这被显示出。当x增加到0.3时,onlyLa(Mg,艾尔)并且La_2Al的小数量存在。当x是0.4时,La_2Al阶段消失,合金包含两La(Mg,艾尔)并且La(艾尔,Mg)_2洗阶段。(La_(0.9)Mg_(0.1))_3Al并且(La_(0.7)Mg_(0.3))_3Al合金能被氢的吸收在473K分解成LaH_3,MgH_2,和La_2Al_5。
简介:PolycrystallinesamplesofLa12x(Sr12yAgy)xMnO3(y=0.0,0.2,0.4,0.6,1.0)werepreparedbythesolid-statereactionmethod.ThetemperaturestabilityofmagnetoresistanceandmagnetoresistanceenhancementinLa1-x(Sr1-yAgy)xMnO3systemwithbothunivalentandbivalentelementsdopedatAsiteandwithunchangedvalueofMn3+/Mn4+ratiowereexploredthroughthemeasurementsofX-raydiffractionpatterns,magnetiza-tion-temperature(M-T)curves,resistivity-temperature(q-T)curvesandmagnetoresistance-temperature(MR-T)curves.Theresultsareasfollows:therearetwopeaksintheq-TcurvesofthesampleswithAgdoping,oneiscausedbyresistancechangeduringtheparamagnetism-ferromagnetismtransition,andtheotherisfromboundary-dependentscatteringofconductionelectronsontheboundariesofgrains.ThepeakvalueofMRincreaseswithincreasingAgdopingcontent,anditincreasesfrom8.2%fory=0.2to29.6%fory=1.0underthemagneticfieldofB=0.8T;MRremainsaconstantof12%inthetemperaturerangeof218-168Kforthesamplewithy=1.0,andthetemperaturestabilityofMRisinfavorofthepracticalapplicationofMR.
简介:Thecorrosionfatiguebehaviorofepoxy-coatedMg–3Al–1Znalloywasinvestigatedinairand3.5wt%NaClsolution.Epoxycoatingasanewmethodwasusedtoimprovethecorrosionfatiguepropertyofthematerial.Resultsshowthatthefatiguelimit(FL)ofthecoatedspecimensishigherthanthatoftheuncoatedspecimensin3.5wt%NaClsolutionbecauseofthestrengtheningandblockingfunctionsoftheepoxycoating.TheFLofthecoatedspecimensin3.5wt%NaClsolutionisashighasthatinair.Itimpliesthatthecoatedspecimensarenotassensitivetotheenvironmentasthemagnesiumalloy.Thelowtensilestrengthandtheshortelongationofthepureepoxycoatingleadtothatthefatiguecrackofthecoatedspecimenisalwaysinitiatedfromtheepoxy-coatingfilmPoresandpinholesacceleratethefatiguecrackinitiationprocess.PinholesarecausedbythecorrosionreactionsbetweentheepoxycoatingandtheNaClsolution.
简介:针对激光直接沉积修复的1Cr15Ni4Mo3N钢零件在磁粉检测时出现的磁痕现象,采用接触通电、湿磁粉连续法,对设计的试样进行磁粉检测,确定磁痕显示位置;利用光学显微镜对磁痕显示处形貌及修复接头和组织进行观察和研究,分析磁痕的性质和形成原因。研究发现:激光直接沉积修复1Cr15Ni4Mo3N钢在磁粉检测过程中与修复区外轮廓完全重合的磁痕显示是伪磁痕显示,主要是由修复区与基体中奥氏体含量的差异造成的。