学科分类
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80 个结果
  • 简介:TheBrenner-LJpotentialisadoptedtodescribetheinteractionbetweenC36clustersanddiamondsurface,andthedepositionmechanismofmulti-C36clustersonthediamondsurfaceisalsostudiedbyusingthemethodofmoleculardynamicssimulation.Thesimulationresultsshowthatthecompetitioneffectsoftwointeractions,i.e.theinteractionbetweenclusterandclusterandtheinteractionbetweenclusterandcrystalplane,arestudied,andthentheinfluenceofthesecompetitioneffectsonC36clusterdepositionisanalysed.Thefindingisthatwhenanincidentenergyisappropriatelychosen,C36clusterscanbechemicallyadsorbedanddepositedsteadilyonthediamondsurfaceintheformofsingle-layer,andinthedepositionprocessthemulti-C36clusterspresentaphenomenonofenergytransmission.Theexperimentalresultshowsthatatatemperatureof300K,inordertodepositC36clustersintoasteadynano-structuredsingle-layeredfilm,theoptimalincidentenergyisbetween10and18eV,iftheincidentenergyislargerthan18eV,theC36clusterswillbedepositedintoanislandnano-structuredfilm.

  • 标签: 单层碳膜 纳米材料 纳米结构 沉积机制
  • 简介:Synergisticeffectsoflayereddoublehydroxide(LDH)withintumescentflameretardanct(IFR)ofphosphorus-nitrogen(NP)compoundinthepolypropylene/ethylene-propylene-diene/IFR/LDH(PP/EPDM/IFR/LDH)nanocompositesandrelatedpropertieswerestudiedbyX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM),scanningelectronmicroscopy(SEM),limitingoxygenindex(LOI),UL-94test,conecalorimetertest(CCT)andthermo-gravimetricanalysis(TGA).TheXRDandTEMresultsshowthattheintercalatedand/orexfoliatednanocompositescanbeobtainedbydirectmelt-intercalationofPP/EPDMintomodifiedLDHandthatLDHcanpromotetheIFRadditiveNPtodispersemorehomogeneouslyinthepolymermatrix.TheSEMresultsprovidepositiveevidencethatmorecompactcharredlayerscanbeobtainedfromthePP/EPDM/NP/LDHsamplethanthosefromthePP/EPDM/LDHandPP/EPDM/NPsamplesduringburning.TheLOIandUL-94ratingtestsshowthatthesynergeticeffectsofLDHwithNPcaneffectivelyincreasetheflameretardantpropertiesofthePP/EPDM/NP/LDHsamples.ThedatafromtheCCTandTGAtestsindicatethatthePP/EPDM/NP/LDHsamplesapparentlydecreasetheHRRandMLRvaluesandthusenhancetheflameretardantpropertiesandhavebetterthermalstabilitythanthePP/EPDM/LDHandPP/EPDM/NPsamples.

  • 标签: 膨胀型阻燃聚丙烯 层状双金属氢氧化物 三元乙丙橡胶 纳米复合材料 膨胀型阻燃剂 国土资源部
  • 简介:Layereddoublehydroxides(LDHs)withhydrotalcite-typestructurecontainingFe3+,Al3+andMg2+werepreparedbymeansofacoprecipitationmethod.Theproductswerecharacterizedbyelementanalysis,X-raypowderdiffractionandtransmissionelectronmicroscopy.Itwasfoundthatevenifthemolarratioofn(Fe+Al)/n(Fe+Al+Mg)>0.33,yetapurehydrotalcite-likecompound(HTlc)phasewasgainedwhenn(Fe)/n(Al+Mg+Fe)≤0.30andn(Al)/n(Al+Mg+Fe)≤0.30;theAl(OH)3phaseappearedintheproductswhenn(Al)/n(Al+Mg+Fe)>0.30;andanamorphousphaseemergedwhenn(Fe)/n(Al+Mg+Fe)>0.33.TheseresultsshowthatthereisnoconcentrationsuperpositioneffectbetweenFe3+andAl3+onthecrystallinestateoftheproducedsamples.Inourpreviouswork,theconcentrationsuperpositioneffectbetweenZn2+andMg2+inthesynthesisofZn-Mg-Al-LDHswasfound.ForthepreparedFe-Al-Mg-LDHssamples,thevalueoflatticeparameteraisbetween0.30-0.32nm;andthevalueoflatticeparametercisbetween2.30-2.47nm,thebasalspacingisintherangeof0.76-0.83nm.Whentheratioofn(Fe)/n(Al)isaconstant,thevaluesofaandcincreasewiththeincreaseoftheMg2+contentoftheproducedsamples.Themeanparticlesizeandthemeancrystalgrainweredeterminedbyvirtueofaparticle-sizeinstrument,XRD-ScherrerformulaandTEMmethod,respectively.

  • 标签: 羟化物 水滑石结构 LDHS 元素分析 摩尔比
  • 简介:Aperiodiclayeredmedium,withunitcellsconsistingofadielectricandanelectromagnetically-inducedtransparency(EIT)-basedatomicvapor,isdesignedforlightpropagationmanipulation.Consideringthatadestructivequantuminterferencerelevanttoatwo-photonresonanceemergesinEIT-basedatomsinteractingwithbothcontrolandprobefields,anEIT-basedperiodiclayeredmediumexhibitsaflexiblefrequency-sensitiveopticalresponse,whereaverysmallvariationintheprobefrequencycanleadtoadrasticvariationinreflectanceandtransmittance.ThepresentEIT-basedperiodiclayeredstructurecanresultincontrollableopticalprocessesthatdependsensitivelyontheexternalcontrolfield.Thetunableandsensitiveopticalresponseinducedbythequantuminterferenceofamulti-levelatomicsystemcanbeappliedinthefabricationofnewphotonicandquantumopticaldevices.Thismaterialwillalsoopenagoodperspectivefortheapplicationofsuchdesignsinseveralnewfields,includingphotonicmicrocircuitsorintegratedopticalcircuits.

  • 标签: coherent LAYERED TRANSPARENCY INTERACTING PHOTONIC MANIPULATION
  • 简介:InsituhighpressureenergydispersiveX-raydiffractionmeasurementsonlayeredperovskite-likemanganateCa3Mn2O7underpressuresupto35GPahavebeenPerformedbyusingdiamondanvilcellwithsynchrotronradiation.Theresultsshowthatthestructureoflayeredperovskite-likemanganateCa3Mn2O7isunstableunderpressureduetotheeasycompressionofNaCl-typeblocks.ThestructureofCa3Mn2O7underwenttwophasetransitionsunderpressuresintherangeof0-35GPa.Onewasatabout1.3GPawiththecrystalstructurechangingfromtetragonaltgoorthorhombic.Theotherwasatabout9.5GPawiththecrystalstructurechangingformorthorhombicbacktoanothertetragonal.

  • 标签: 高压 X射线衍射 Ca3Mn2O7 钙钛矿结构 锰酸盐晶体 相变
  • 简介:Usingthetimereversal(TR)-reversetimemigration(RTM)mixedmethod,thenumericalanalysistowardstheacousticfieldfordetectionandlocationoftargetsinlayeredmediaisperformed.Firsttheapproachesandstepsofthenumericalanalysisandsimulationforacousticfieldareproposed,then,theacousticfielddistributionofsingletargetandmultipletargetsarefurthercomputedbyusingtheapproachesofsingleemission-multiplereceivingandmultipleemission-multiplereceiving.Thenumericalsimulationresultsindicatethattargetdetectionandlocationcanbewellrealized.Bycomparison,goodresultsareobtainedfromthebothtwoapproaches,butlargetime-consumingisobservedinwayofmultipleemission-multiplereceiving,andsowouldbeunacceptable.Additionally,theimprovedwayisalsoproposedformultipletargetdetection.

  • 标签: 目标探测 层状介质 逆时偏移 定位 混合法 反时限
  • 简介:ThisstudyproposesaGreen’sfunction,anessentialrepresentationofwater-saturatedgroundundermovingexcitation,tosimulategroundbornevibrationfromtrains.First,generalsolutionstothegoverningequationsofporoelasticmediumarederivedbymeansofintegraltransform.Secondly,thetransmissionandreflectionmatrixapproachisusedtoformulatetherelationshipbetweendisplacementandstressofthestratifiedground,whichresultsinthematrixoftheGreen’sfunction.ThentheGreen’sfunctioniscombinedintoatrain-track-groundmodel,andisverifiedbytypicalexamplesandafieldtest.Additionalsimulationsshowthatthecomputedgroundvibrationattenuatesfasterintheimmediatevicinityofthetrackthaninthesurroundingarea.Thewavelengthofwheel-railunevennesshasanotableeffectoncomputeddisplacementandporepressure.Thevariationofvibrationintensitywiththedepthofgroundissignificantlyinfluencedbythelayeringofthestratasoil.WhenthetrainspeedisequaltothevelocityoftheRayleighwave,theMachconeappearsinthesimulatedwavefield.TheproposedGreen’sfunctionisanappropriaterepresentationforalayeredgroundwithshallowgroundwatertable,andwillbehelpfultounderstandthedynamicresponsesofthegroundtocomplicatedmovingexcitation.

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  • 简介:Inthepresentwork,anovelhybridcompositecomposedofTi-aluminidemulti-layeredpartandcontin-uous-SiCf-reinforcedTi-matrixpartusingavacuumhotpressing/hotisostaticpressure(VHP/HIP)sinteringprocesswassynthesized.Then,thedamagetolerancebehaviorofthishybridcompositewasstudiedbytensiletestsandinsituscanningelectronmicroscopy(SEM)three-pointbendingtests.Theresultsindicatethatthemechanicalpropertiesandcrackpropagationofthehybridcompositearestronglyinfluencedbytheextrinsictoughnessmecha-nism.Indetail,thecrackdeflectionofmulti-layeredcompositeandstrengtheningeffectofSiCf-reinforcedmatrixcompositeareobservedinthehybridcomposite.Owingtothestrengtheningeffectofcontinuous-SiCrre-inforcedTi-matrixpart,thetensilestrengthofhybridcompositeismuchhigherthanthatofneatTi-aluminidemulti-layeredcomposite.Furthermore,itisfoundthattheoptimaldamagetoleranceabilityisoptimizedwhenthenotchpositionislocatedattheTi-aluminidemulti-layeredpartduetothecrackdeflectionofmulti-layeredstructure.

  • 标签: Hybrid COMPOSITE Synthesis Mechanicalproperties In SITU
  • 简介:基于AB_5的氢存储薄电影(LaNi_(4.25)Al_(0.75)),由dc磁控管劈啪作响的扔的onCu底层在这研究被调查。X光检查衍射(XRD)表明层的微观结构在晶形。SEM和AFM分析证明这部电影看起来与近似在nmdiameter的15-40的众多的随机大小的毛孔相当不平。这部电影的结构的稳定性被DSC,XRD,andS他们,它显示这部电影在500K左右下面维持了它的结构的稳定性,和网络结构的联合分析检验在为30min在700K被加热以后在这部电影上被观察。这些电影的Electrochemicalhydrogen存储性质被模仿的电池测试调查。单人赛分层的LaNi_(4.25)Al_(0.75)大批拍摄类似于典型AB_5合金的展出电气化学的氢存储性质,这被发现,并且这部电影的最大的分泌物能力关于220mAh/g。在20个控告/解除周期以后,小塑造针的铝氧化物在电影表面的一些部分上被形成。

  • 标签: 储氢薄膜 磁控溅射 结构稳定性 电气化学性质 LaNi4.25Al0.75
  • 简介:ThisstudyshowsthepreparationofaTiO_2coatedPt/C(TiO_2/Pt/C)byatomiclayerdeposition(ALD),andtheexaminationofthepossibilityforTiO_2/Pt/Ctobeusedasadurablecathodecatalystinpolymerelectrolytefuelcells(PEFCs).CyclicvoltammetryresultsrevealedthatTiO_2/Pt/Ccatalystwhichhas2nmprotectivelayershowedsimilaractivityfortheoxygenreductionreactioncomparedtoPt/Ccatalystsandtheyalsohadgooddurability.TiO_2/Pt/Cpreparedby10ALDcyclesdegraded70%after2000Accelerateddegradationtest,whilePt/Ccorroded92%inthesameconditions.TiO_2ultrathinlayerbyALDisabletoachieveagoodbalancebetweenthedurabilityandactivity,leadingtoTiO_2/Pt/CasapromisingcathodecatalystforPEFCs.ThemechanismoftheTiO_2protectivelayerusedtopreventthedegradationofPt/Cisdiscussed.

  • 标签: 聚合物电解质燃料电池 纳米二氧化钛 阴极催化剂 原子层沉积 耐久性 铂碳
  • 简介:象lumped参数模型那样的分离模型和有限元素模型广泛地在地震的土壤扩大的解决方案被使用。然而,任何一个模型都精确地不估计土壤沉积物的自然频率,也不模仿一抑制频率独立。这研究基于模式等价方法为分层的土壤沉积物的一个维的粘弹性的反应分析开发一个新分离模型。新分离模型是一系列集中的群众,弹簧和缓冲筒与一种特殊配置描绘的一个一个维的相等的multi-degree-of-freedom(MDOF)系统。相等的MDOF系统的动态反应是导出的经分解,物理参数以形式的性质被提出。相等的MDOF系统与可得到的理论解决方案通过扩大函数的比较被验证。在相等的MDOF系统的自由(DOF)的度的适当数字被估计。有存在的相等的MDOF系统的比较研究分离模型被执行。建议相等的MDOF系统罐头确切介绍土壤存款抑制的自然频率和hysteretic并且向更精确的结果提供更少DOF,这被显示出。

  • 标签: 土壤沉积物 反应分析 粘弹性 相等 系统 MDOF
  • 简介:Thispaperstudiesthree-dimensionaldiffractionofobliquelyincidentplaneSHwavesbytwininfinitelylongcylindricalcavitiesinlayeredporoelastichalf-spaceusingindirectboundaryelementmethod.Theapproachisvalidatedbycomparisonwiththeliterature,andtheeffectsofcavityinterval,incidentfrequency,andboundarydrainageconditiononthediffractionarestudiedthroughnumericalexamples.Itisshownthat,theinteractionbetweentwocavitiesissignificantandsurfacedisplacementpeaksbecomelargewhentwocavitiesareclose,andthesurfacedisplacementmaybesignificantlyamplifiedbytwincavities,andtheinfluencerangewithlargeamplificationcanbeaswideas40timesofthecavityradius.Surfacedisplacementsindryporoelasticcaseandsaturatedporoelasticcaseswithdrainedandundrainedboundariesareevidentlydifferentundercertaincircumstances,andthedifferencesmaybemuchlargerthanthoseinthefree-fieldresponse.

  • 标签: 平面SH波 多孔介质 空间三维 斜入射 圆柱形 无限长
  • 简介:钴(公司)在自然地发生在重要数量存在锰(Mn)氧化物并且改变Mn氧化物晶体的生长。四分层的Mn氧化物,Na-buserite(Na公共汽车)并且三共同做从Mn的氧化准备的Na-buserite样品(哦)2与5%,10%,和20%Co/(Mn+公司)臼齿的比率(5Co-Na-bus,10Co-Na-bus,和20Co-Na-bus),被用来准备todorokite,地球的表面上的普通Mn氧化物,把Mg2+/Co2+离子用作一个模板。结果证明todorokites能被交换Mg2+的非做的Na-buserite的倒流处理获得,三共同做在气压的Na-buserites。然而,todorokites的形成被交换Co2+的Na公共汽车,5Co-Na-bus,和10Co-Na-bus样品的倒流处理禁止。相反,todorokite被交换Co2+的20Co-Na-bus样品的倒流处理在气压下面获得。X光检查光电子光谱学分析证明做的公司在做的Na-buserites的MnO6层作为Co3+存在。在MnO6层的代替的Co3+的数量可以作为一个模板用Co2+离子在buserite的变换起一个关键作用到todorokite。

  • 标签: 层状锰氧化物 CO2交换 钙锰矿 镁离子 模板 掺钴
  • 简介:AnewlayeredCu-basedoxychalcogenideBa3Fe2O5Cu2S2hasbeensynthesizedanditsmagneticandelectronicpropertieswererevealed.Ba3Fe2O5Cu2S2isbuiltupbyalternativelystacking[Cu2S2]2-layersandironperovskiteoxide[(FeO2)(BaO)(FeO2)]2-layersalongthecaxisthatareseparatedbybariumionswithFe3+fivefoldcoordinatedbyasquare-pyramidalarrangementofoxygen.Fromthebondvalencearguments,weinferredthatinlayeredCuCh-based(Ch=S,Se,Te)compoundsthe+3cationinperovskiteoxidesheetprefersasquarepyramidalsite,whilethelowervalencecationprefersthesquareplanarsites.Thestudiesonsusceptibility,transport,andopticalreflectivityindicatethatBa3Fe2O5Cu2S2isanantiferromagneticsemiconductorwithaNe′eltemperatureof121Kandanopticalbandgapof1.03eV.Themeasurementofheatcapacityfrom10Ktoroomtemperatureshowsnoanomalyat121K.TheDebyetemperatureisdeterminedtobe113K.TheoreticalcalculationsindicatethattheconductionbandminimumispredominantlycontributedbyO2pand3dstatesofFeionsthatantiferromagneticallyarrangedinFeO2layers.TheFe3dstatesarelocatedatlowerenergyandresultinanarrowbandgapincomparisonwiththatoftheisostructuralSr3Sc2O5Cu2S2.

  • 标签: 钙钛矿型氧化物 铁磁半导体 光学带隙 德拜温度 电子性质 阳离子
  • 简介:Ameshlessradialbasisfunction(RBF)collocationmethodbasedontheEringennonlocalelasticitytheoryisdevelopedtocalculatethebandstructuresofternaryandquaternarynanoscalemulti-layeredphononiccrystals(PNCs)withfunctionallygraded(FG)interlayers.Detailedcalculationsareperformedforanti-planetransversewavespropagatinginsuchPNCs.TheinfluencesofFGandhomogeneousinterlayers,componentnumber,nonlocalinterfaceimperfectionsandnanoscalesizeoncut-offfrequencyandbandstructuresareinvestigatedindetail.Numericalresultsshowthatthesefactorshavesignificanteffectsonbandstructuresatthemacroscopicandmicroscopicscales.

  • 标签: 非局部弹性理论 径向基函数 能带结构 纳米尺寸 声子晶体 功能梯度
  • 简介:Thecombinationofboth4,4′-bipyridine(4,4′-bipy)anddihydrogenphosphateanionligandswithcopper(Ⅱ)resultsintheformationofanovellayeredcompoundCu(4,4′-bipy)2(H2PO4)2(H2O)2.ThecrystalstructurecomprisesdiscreteneutralCu(4,4′-bipy)2(H2PO4)2(H2O)2units.Thecopperatom,locatedonthecrystallographictwofoldaxis,iscoordinatedwithtwonitrogenatomsofterminal4,4′-bipyligandsandtwowatermoleculesattheequatorialpositions,andtwodihydrogenphosphateoxygenatomsattheaxialpositions,forminganelongatedoctahedron.Thecomplexisatwo-dimensionaldistortedrhomboidalnetworkpossessingtwokindsofrhomboidswithdimensionsofca.1.6792nm×0.3203nmand1.2778nm×0.3198nm,respectively.Thetwo-dimensionalnetworksarestackedparallellyoneachotheralongc-axistogiveanextendedthree-dimensionalchannelnetworkwithaninterlayerdistanceofca.0.5030nm.Crystaldata:triclinic,spacegroupP-1,a=1.0253(2)nm,b=1.4501(3)nm,c=0.79715(16)nm,α=97.91(3)°,β=90.99(3)°,γ=85.54(3)°,V=1.1703(4)nm3,Z=2,R=0.0892,wR=0.2451.

  • 标签: 磷酸盐 4 4'-双吡啶 铜(Ⅱ)复合物 沟渠构造 热液合成