简介:Grapheneistwodimensionalmaterialswhichismadeofhoneycombedcarbonatoms.Itattractsextensiveinterestsforitswonderfulcharacteristicsthatmakethegrapheneapotentialcandidateinfieldsofmicroelectronicsproduction,moleculedetection,desalinationandDNAsequencing.Highlychargedion(HCI)hashugepotentialenergyforpeelingoffelectrons.Wheninteractingwithsolidsurface,theHCIdistortedthesolidlatticeviapotentialdepositionandthenthenanostructureswereformedonthesolidsurface.TheHCIwasexpectedasatoolforsurfacemodification.Inthiswork,HOPGandgraphemewereirradiatedwithXeq+andArq+ions.ThetypicalRamanspectraofgrapheneandHOPGirradiatedwithhighlychargedionswereshowninFig.1.TheDpeakappearedat1335cm??1onthespectraofgrapheneirradiatedwithhighlychargedions.TheintensityofDpeakincreasedwithfluence.TheratioofintensityofDpeaktothatofGpeakvariedwithfluenceinFig.2.Theratioroselinearlywiththesquarerootoffluencewhenfluencewaslow.Theratiosaturatedwhentheirradiationfluencewashigh.Thecriticalfluencedependedonthechargestateofion.Thehigherchargestateitwas,thelowercriticalfluenceitwouldbe.
简介:MicrodosimetricSpectrumandRadialDoseDistributionof239PnorRayinCH4Gas¥ZhuLianfang;LiXuekan;ChenXuebing;HeYusheng;SuYouwuand...
简介:Duetolowactivationcharacteristics,desirablehigh-temperaturestrength,goodresistancetoradiationdamageandusablefabricationproperties,vanadium(V)alloysareattractivecandidatestructuralmaterialsforfusionreactors[1].Irradiationinducedhardening/embrittlementatlowtemperatureisamajorproblemforthematerialsapplicationinfusionreactor[2].Inthisstudy,H/Heionswithvariousenergieswereusedtoirradiateapurevanadium(V)andaValloy(V-4Ti)toobtainadamageplateaufromsamplesurfacetothedepthof1.5m,asshowninFig.1[3].Thedetailsofirradiationparameters(energies,fluences)forHandHeionsareshowninTable1.NanoindentationwasperformedtoinvestigatethehardeningbehaviorofV-4TialloyandpureVunderirradiation.
简介:TheenergyresponsesofKaoftwotypesofcylindricalG-Mcountertubeswerecalculatedusinganelectron-photoncascadeMonteCarlocode,EGS4.OnetypeoftheG-McountertubeswasGJ4401(sensitivelength9cm,diameter1cm),theotherwasJ5(sensitivelength2cm,diameter0.3cm),therestrictedsamplingtechniqueofsourcephotonwasused.Goodtendencyagreementsbetweenthesimulationsandexperimentswereachievedforgammaradiationwithenergiesrangingfrom40keVto1.25MeV.ForGJ4401,thedifferenceofresponsebetweensimulationsandexperimentsat662keVwas34%andforJ5thedifferencewas27%.
简介:Highlychargedions(HCIs)carryingamountofpotentialenergywillproducesomenewphysicalphenomenabecausethepotentialenergywillbedepositedintoaverysmallvolumewithinaveryshorttime.WewouldapplythecalorimetricmethodtostudytheenergydepositionofHCIs[1;2].Hereinweintroducethenewsetupforcalorimetricmeasurementforthepotentialenergydepositionofhighlychargedionsat320kVHighlyChargedIonsPhysicsExperimentalPlatform.Thesetupwasconstructedby3parts:theDewar,theelectricaltemperaturecontrollerandthemainpart.ThediamondtargetwasconnectedtotheLN2cooledheatsinkby4copperwiresandaPlatinumtemperaturesensorwasgluedtotherearsideofthetarget.AsshowninFig.1.
简介:Two-dimensional(2-D)BiVO4nanosheets-graphene(GR)compositeswithdifferentweightadditionratiosofGRhavebeenpreparedviaafacilewetchemistryprocess.X-raydiffraction(XRD),Ramanspectra,X-rayphotoelectronspectra(XPS),UV-visdiffusereflectancespectra(DRS),field-emissionscanningelectronmicroscopy(FE-SEM),transmissionelectronmicroscopy(TEM),nitrogenadsorption-desorption,transientphotocurrentresponseandphotoluminescence(PL)spectrawereemployedtodeterminethepropertiesofthesamples.ItisfoundthatBiVO4nanosheetscouldpavewellonthesurfaceofgraphenesheets.BiVO4nanosheets-GRcompositeswithaproperadditionamountofGRexhibitedhigherphotocatalyticactivitythanbareBiVO4nanosheetstowardliquid-phasedegradationofrhodamineB(RhB)andmethylorange(MO)undervisiblelightirradiation.TheenhancementofphotocatalyticactivitiesofBiVO4nanosheets-GRcompositescanbeattributedtotheeffectiveseparationofphotoexcitedelectron-holepairs.Thisworknotonlyprovidesasimplestrategyforfabricatingspecific2-Dsemiconductor-2-DGRcomposites,butalsoopensanewwindowofsuch2-Dsemiconductor-2-DGRcompositesasvisiblelightphotocatalyststowardanimprovedvisiblelightphotoactivityinpurifyingpollutedwaterresources.
简介:Isochronousmassspectrometry(IMS)instorageringsisapowerfultoolformassmeasurementsofexoticnuclewithveryshorthalf-livesdowntoseveraltensofmicroseconds,usingamulticomponentsecondarybeamseparatedin-ightwithoutcooling.However,theinevitablemomentumspreadofsecondaryionslimitstheprecisionofnuclearmassesdeterminedbyusingIMS.
简介:CO2photoreductionisanattractiveprocesswhichallowsthestorageofsolarenergyandsynthesisofsolarfuels.Manydifferentphotocatalyticsystemshavebeendeveloped,whilethealternativephoto-reactorsarestillinsufficientlyinvestigated.Inthiswork,photoreductionofCO2withH2OintoCH4wasinvestigatedinamodifiedconcentratingsolarreactor,usingTiO2andPt/TiO2asthecatalysts.TheTiO2andPt/TiO2sampleswereextensivelycharacterizedbydifferenttechniquesincludingpowderX-raydiffraction(XRD),N2adsorption/desorptionandUV–visabsorption.ThecatalyticperformanceoftheTiO2andPt/TiO2samplesinthegasphasewasevaluatedunderunconcentratedandconcentratedXe-lamplightandnaturesolarlightwithdifferentconcentratingratios.VariousparametersofthereactionsystemandthecatalystswereinvestigatedandoptimizedtomaximizethecatalyticperformanceofCO2reductionsystem.Comparedwiththenormallightirradiation,theTiO2andPt/TiO2samplesshowhigherphotocatalyticactivity(about6–7times)forreducingCO2intoCH4underconcentratedXe-lamplightandnaturesolarlight.Intherangeofexperimentallightintensity,itisfoundthattheconcentrationofthelightmakesitsuitableforthecatalyticreaction,andincreasestheutilizationefficiencyoftheTiO2andPt/TiO2sampleswhiledoesnotdecreasethequantumefficiency.
简介:COandformaldehyde(HCHO)oxidationreactionswereinvestigatedovermesoporousAg/Co3O4catalystspreparedbyone-pot(OP)andimpregnation(IM)methods.Itwasfoundthattheone-potmethodwassuperiortotheimpregnationmethodforsynthesizingAg/Co3O4catalystswithhighactivityforbothreactions.ItwasalsofoundthatthecatalyticbehaviorofmesoporousCo3O4andAg/Co3O4catalystsforthebothreactionswasdifferent.AndtheadditionofsilveronmesoporousCo3O4didnotalwaysenhancethecatalyticactivityoffinalcatalystforCOoxidationatroomtemperature(20C),butcouldsignificantlyimprovethecatalyticactivityoffinalcatalystforHCHOoxidationatlowtemperature(90C).Thehighsurfacearea,uniformporestructureandtheprettygooddispersiondegreeofthesilverparticleshouldberesponsiblefortheexcellentlow-temperatureCOoxidationactivity.However,forHCHOoxidation,theadditionofsilverplayedanimportantroleintheactivityenhancement.AndthesilverparticlesizeandthereducibilityofCo3O4shouldbeindispensableforthehighactivityofHCHOoxidationatlowtemperature.
简介:NativedefectsinHfSiO_4areinvestigatedbyfirstprinciplescalculations.TransitionlevelsofnativedefectscanbeaccuratelydescribedbyemployingthenonlocalHSE06hybridfunctional.Thismethodologyovercomesthebandgapproblemintraditionalfunctionals.BybandalignmentsamongtheSi,GaAsandHfSiO_4,weareabletodeterminethepositionofdefectlevelsinSiandGaAsrelativetotheHfSiOibandgap.Weevaluatethepossibilityofthesedefectsactingasfixedcharge.Nativedefectsleadtothechangeofvalenceandconductionbandoffsets.Gateleakagecurrentisevaluatedbythebandoffset.Inaddition,wealsoinvestigatediffusionsofnativedefects,anddiscusshowtheyaffecttheMOSdeviceperformance.
简介:Continuoussiliconcarbidefiberreinforcedsiliconcarbide(SiCf/SiC)compositeshavebeenconsideredtobecandidatematerialsofhightemperaturestructuralapplicationinaerospace,energyconservationandpowergenerationduetotheexcellenthightemperaturemechanicalproperties,goodfractureresistance,corrosionresistanceandthermodynamicstability.Furthermore,duetothehighthermalstability,lowinducedradioactivity,quickdecayofactivityandlowafterheat,SiCf/SiCcompositeshavebeenrecognizedasthepromisingmaterialsoffissionandfuturefusionreactors.SiCf/SiCcompositesarecomposedofSiCfiberandSiCmarixmaterials.Radiationresistance,oxidationtolerance,fracturetoughnessandtensilestrengthofSiCfiberhaveadirectimpactontheSiCf/SiCcompositesperformance.
简介:Inrecentyears,themagneticmultilayerednanomaterialshavebeenextensivelystudiedforelectronics[1],ultrahightensilestrength[2],highstoragemedia[3],andmicrowavedevices[4]sincethegiantmagnetoresistance(GMR)effectwasfoundin1988.Asamemberof1Dnanostructuredmaterials,theferromagneticandnonmagneticmultilayernanowiresalsoexhibittremendouspotentialapplicationsinmanyfieldsduetotheiruniquemagneticandelectricalproperties.Inthiswork,theCu/NimultilayernanowirearraysarepreparediniontracktemplatewithelectrodepositionmethodandanewfacilemethodisfirstintroducedtoeasilyconfirmthedifferentlayerthicknessandcomponentbyremovingthenonmagneticlayerofCu.
简介:Ti6Al4Visawidelyappliedinmedicalimplantssuchasbone,joint,andteethduetoitsexcellentmechanicalproperties,corrosionresistance,plasticityandthebiocompatibilityofthesurfaceoxide.However,thenativesurfaceoxidefilmisquitethin(about5nm)andtechniquessuchasmicroarcoxidation,plasmasprayedhydroxyapatitaeandplasmaimmersionionimplantationareusedtosynthesizethickersurfacetitaniumoxide.
简介:YbxY1-xAl3(BO3)4(x=0.1,0.07and0)crystalshavebeengrownbythefluxmethod.ThegrowthdefectsofYbxY1-xAl3(BO3)4crystalsweredetectedbyX-raytopography.ItisfoundthattheperfcetionofYbYABcrystalwithlowYbdopantisbetterthanthatwithhighYbdopant.InYb0.1Y0.9Al3(BO3)4crystal,growhtbands,growthboundaries,grown-indislocationsandinclusionswereobserved.Howver,thedensitiesofgrowthdefectsforYb0.07Y0.93Al3(BO3)4andYAl3(BO3)4arelowandnoobviousinclusionsareobservedinthesecrytals.Inaddition,growthtwinswrerdetectedinYbxY1-xAl3(BO3)4crystalbyusingthechemicaletchingmethod.ItisfoundthatthegrowthtwinsoccurfrequentlyinYb0.01Y0.9Al3(BO3)4crystalwhereasnogrowthtwinappearsinYAl3(BO3)4crystal.Basedontheexperimentalobservations,theformationmechanismofgrowthtwinsisdiscussed.Inthemeantime,theeffectivemeasuresforreducingthegrowthtwinsanddefectsareproposed.2001ElsevierScienceB.V.Allrightsreserved.
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简介:CO2methanationhasbeenahottopicbecauseofitsimportantapplicationinthespacecraftandpotentialutilizationofcarbondioxide.Nickelcatalystisactiveforthisreaction.However,itsactivitystillneedstobeimproved.Dielectricbarrierdischarge(DBD)plasma,initiatedatambientconditionandoperatedat~150°C,hasbeenemployedinthisworkfordecompositionofnickelprecursortoprepareNi/MgAl2O4.Theplasmadecompositionresultsinhighdispersion,uniquestructure,enhancedreducibilityofNiparticlesandpromotedcatalyst-supportinteraction.AnimprovedactivityofCO2methanationwithahigheryieldofmethanehasbeenachievedovertheplasmadecomposedcatalyst,comparedtothecatalystpreparedthermally.Forexample,themethaneyieldoftheplasmapreparedcatalystis71.8%at300°Cbutitis62.9%overthethermalpreparedcatalyst.ThecatalystcharacterizationconfirmedthatCO2methanationovertheDBDplasmapreparedcatalystfollowspathwayofCOmethanation.