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:Duetotheremarkablemagnetoresistance(MR)effectonperovskite-typemanganite,magnetoelectronicsandspintronicshavebecomeattractivesubjectsofexperimentalandtheoreticalinvestigationsfortheapplicationpurpose.(La0.9Nd0.1)2/3Ca1/3Mn1-xFexO3(x=0,x=0.05)werepreparedsuccessfullybysol-gelmethod.Thestructure,magneticproperties,andtransportpropertiesofthecompoundswereinvestigated.Themagnetoresistanceeffectdependsonthecompositionandthetemperature.XRDpatternsshowthatthecompoundisasinglephasepolycrystalwithpseudocubicstructure.Alargenegativeisotropicmagnetoresistanceeffectinthesampleswereobservedatlowtemperatureregion.ThemaximumMRofthesampleswas77%and97%,respectively.Itwasmostlikelyduetothescatteringorthetunnelingtransportofspin-polarizedcarriersinlatticeunderstrongmagneticfield.
简介:Thispaperprovesthattheoptimalquadratureformulasoftype(r1,…rn)forWm1isunique,andtheextremalfunctionischaracterizedbyitsoscillatoryproperty.Ontheotherhand,thefundamentaltheoremofalgebraforperiodicmonosplineswithoddmultiplicitiesissolvcd
简介:摘要:社会需求,教学手段的发展,教学技术的更新,教学教育功能的开发,教学设计者的态度和思想,都在影响着当前教育教学效果,提倡以学生发展为目标,建立更加适应学生的教育思想,教学载体多样化,让各具个性的学生,在集中教学中都受益,达到学生全面提升的效果,是我们所追求的课堂教学目标。本文提出,对于每次课的主体知识点,不能“昙花一现”,也不要单线联系,要在“双案——四线”中同时并进,各条线不是互相取代,更不是相互抵触,而是“从A地到B地的并联”关系,知识结构中有,问题练习中有,课本中有,学案中有,ppt课件中仍然有,预习时涉及,互动探究时深入,收尾训练时巩固,坚持每一节课的节奏都是“合奏”与“混响”,这些“自助餐”式的学习载体,总有合适的“音频”或“食品”能够引起学生的“食欲”或“共鸣”。老师就是“编创者兼音乐指挥”,舞台上各个声源如何更和谐,何时发声,发什么样的调子,要融入作曲创编者和指挥者的才智,才可以欣赏到优美的交响乐。一节课的内容看起来不多,但学生的理解情况多,要让每个学生都得到最好的教育,教师就必须坚持多角度付出,无论“课本画块描线”“系统制作课件”“精心编制学案”“知识分层主线”“问题例题训练”“音像动画图片”“生生动态答辩”“引导学生会战”等等,这一宗才构成备课的教学方案,才能为一节优质课创造稳固的基础。在教学管理与实施中,教育的节点和情景信息都不是固定的,更不可能把学情都看作是一致的,在分层教育活动时,无论是人、事、资源、行为,多采用“3+3+3”的划分去操作,又可以将教育的精准度提升三倍以上。
简介:
简介:Layeredcathodematerialsofhigh-temperaturelithiumbatteries,LiNi1/3Mn1/3Co1/3O2aresynthesizedbyasol-gelmethodwithvariationinfinalsinteringtemperatureforboreholeapplications.Thestructure,morphologyandhigh-temperaturedischargeperformanceoftheseresultingproductsareinvestigatedbyX-RayDiffraction(XRD),scanningelectronmicroscopy(SEM),laserparticlesizeanalysis,galvanostaticandpulsedischarge.Theresultsofstructuralanalysisindicatethatthesamplesinteredat800℃hasthecharacteristicsofgoodcrystallinity,narrowsizedistributionandlargespecificsurfaceareaatthesametime.Thedischargeexperimentsalsoindicatethatthissamplehasthebestelectrochemicalproperties,withthemaximumdischargecapacitiesof314.57and434.14mAh·g-1at200and300℃respectivelyandtheminimumcellinternalresistancesatbothtemperatures.
简介:以柠檬酸铁、乙酸锰、乙酸钴和磷酸二氢锂为原料,采用喷雾干燥法制备LiFe1/3Mn1/3Co1/3PO4/C正极材料。采用X射线衍射(XRD),扫面电镜(SEM)以及电化学测试对合成材料进行表征。结果表明,在700℃下焙烧16h合成的LiFe1/3Mn1/3Co1/3PO4/C为结晶良好的橄榄石型结构,颗粒呈球形,球径在0.5-5μm之间。该样品在0.1C倍率下的首次放电比容量为128.3mAh/g,同时具有良好的倍率性能。