简介:Wereportanovelapproachtoobtainingaclassicalblue-greenexcitableCaS:Eu2+phosphorwithdesiredredemissionbymicrowave(MW)firingprocedureintheabsenceofaddingelementalsulphur.ThedisturbingeffectofMWelectromagneticfieldondecompositionofCaSO4intoCaSactivatedbyeuropiumisdistinctlyobservedtogivepurehostphasewithoutaddinganyelementalsulphurandcarbon.ThehostphaseevolutionisobservedtobehighlydependentonthevariationofappliedMWpowerfromX-raydiffraction(XRD)patternsandthecorrespondingphotoluminescence(PL),andamaximumPLintensityat1100WofMWpowerisacquiredfortheobtainedpurerhostphase.Thenon-thermalandnon-equilibriumeffectsbyMWarerevealedtocorrelatewiththeinteractionbetweenpolarstructureofthehostandappliedelectromagneticfield.Theresultsdemonstrateanoptionalproceduretopreparethisred-emittingphosphorinaneffective,environment-friendlyandscalableapproachforphosphorproductionintheapplicationofbio-illuminationforplantcultivationandartificialphotosynthesis.
简介:Bysimultaneouslyemployingbothanelectro-opticmodulatorandcarbonnanotubesaturableabsorber(CNT-SA)inadual-lossmodulator,asubnanosecondsinglemode-lockingpulseunderneathaQ-switchedenvelopewithhighpeakpowerwasgeneratedfromadoublyQ-switchedandmode-locked(QML)Nd:Lu0.15Y0.85VO4laserat1.06μmforthefirsttime,toourknowledge.CNTswithdifferentwallstructures—single-walledCNTs(SWCNTs),double-walledCNTs(DWCNTs),andmulti-walledCNTs(MWCNTs)—wereusedasSAsintheexperimenttoinvestigatethesinglemode-lockingpulsecharacteristics.Atpumppowerof10.72W,themaximumpeakpowerof1.312MWwasobtainedwiththeDWCNT.
简介:NanosizedGa-containingZSM-5zeoliteswerepreparedviaisomorphoussubstitutionandimpregnationfollowedbycharacterizedusingvarioustechniques.Thecatalyticperformanceofthezeolitesforthearomatizationof1-hexenewasinvestigated.TheresultsindicatethatisomorphoussubstitutionpromotestheincorporationofGaheteroatomsintotheframeworkalongwiththeformationofextra-frameworkGaO+species([GaO+]a)thathavestrongerinteractionswiththenegativepotentialoftheframework.Inaddition,basedonthePy-IRresultsandcatalyticperformance,the[GaO+]aspecieswithstrongerLewisacidsitesproducedabettersynergismwithmoderateBr?nstedacidsitesandthusimprovedtheselectivitytoaromaticcompounds.However,theimpregnationresultsintheformationofGa2O3phaseandsmallamountsofGaO+speciesthataremainlylocatedontheexternalsurface([GaO+]b),whichcontributetoweakerLewisacidsitesduetoweakerinteractionswiththezeoliteframework.During1-hexenearomatization,thenanosizedGaisomorphouslysubstitutedZSM-5zeolitesamples(Gax-NZ5)exhibitedbettercatalyticperformancecomparedtotheimpregnatedsamples,andthehighestaromaticyield(i.e.,65.4wt%)wasachievedovertheGa4.2-NZ5sample,whichcontainedwiththehighestGacontent.
简介:Themassesofneutron-defcientnuclidesplayacriticalroleinthecalculationofastrophysicalrapidproton-captureprocesses[1].Neutron-defcientnuclideswithmassnumber∧around80arethelastsetofnuclideswithunknownmassesonthepathwayofvp-process[2].Themassmeasurementofnuclideswouldbeveryuseful.In2016,massesofneutron-defcientnuclides79Y,81Zr,82Zr,83Nband84Nbnucleiwerepreciselymeasureddirectlybytheexperimentalstorage-ringCSReatLanzhou.
简介:Wehavedevelopedacost-effectiveandhighlycompact100-Gb/scoarsewavelengthdivisionmultiplexing(CWDM)transmitteropticalsubassembly(TOSA)usinglens-freehybridintegration.Toachievelargealignmenttolerances,distributedfeedbacklaserdiodes(DFB-LDs)arebutt-coupledtoafour-channelsilica-basedplanarlightwavecircuit(PLC)arrayedwaveguidegrating,withthesiliconsub-mountsandPLCadhesivelybonded.Then,aflexibleprintedcircuitisemployedtoconnecttheinternalDFB-LDsandtheexterioroftheTOSApackageforradiofrequencysignaltransmission,eliminatingtheexpensiveceramicfeed-through.ThepackagedCWDMTOSA,whichis15.8mm×7.0mm×6.0mminsize,showsaside-modesuppressionratioof>40dB,a3dBbandwidthof>18GHz,anderror-freetransmissionwithanaverageopticaloutputpowerof>0dBmanddynamicextinctionratioof>4.0dBat25.78125Gb/sovera10kmsingle-modefiberforallfourlanes.
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.
简介:Afacilestep-by-stepapproachisdevelopedforsynthesizingthehigh-efficiencyandmagneticrecyclableFe_3O_4@SiO_2@Ag@Nitrepang-likenanocomposites.ThismethodinvolvescoatingFe_2O_3nanorodswithauniformsilicalayer,reductionin10%H_2/AratmospheretotransformtheFe_2O_3intomagneticFe_3O_4,andfinallydepositingAg@Nicore-shellnanoparticlesontheL-lysinemodifiedsurfaceofFe_3O_4@SiO_2nanorods.Thefabricatednanocompositesarefurthercharacterizedbyx-raydiffraction,transmissionelectronmicroscopy,scanningelectronmicroscope,Fouriertransforminfraredspectroscopy,andinductivelycoupledplasmamassspectroscopy.TheFe_3O_4@SiO_2@Ag@Nitrepang-likenanocompositesexhibitremarkablyhighercatalyticefficiencythanmonometallicFe_3O_4@SiO_2@AgnanocompositestowardthedegradationofRhodamineB(RhB)atroomtemperature,andmaintainsuperiorcatalyticactivityevenaftersixcycles.Inaddition,thesesamplescouldbeeasilyseparatedfromthecatalyticsystembyanexternalmagnetandreused,whichshowsgreatpotentialapplicationsintreatingwastewater.
简介:Aseriesofoxygenpermeabledual-phasecompositeoxides60wt%Ce0.8Gd0.2O2-δ-40wt%LnBaCo2O5+δ(CGO-LBCO,Ln=La,Pr,Nd,Sm,GdandY)weresynthesizedthroughasol-gelrouteandeffectsoftheLn3+cationsontheirphasestructure,oxygenpermeabilityandchemicalstabilityagainstCO2wereinvestigatedsystemicallybyXRD,SEM,TG-DSCandoxygenpermeationexperiments.XRDpatternsrevealthatthelargerLn3+cations(La3+,Pr3+andNd3+)successfullystabilizedthedouble-layeredperovskitestructureofsinteredLBCO,whilethesmallerones(Sm3+,Gd3+,andY3+)resultedinthepartialdecompositionofLBCOwithsomeimpuritiesformed.CGO-PBCOyieldsthehighestoxygenpermeationflux,reaching2.8×10-7mols-1cm-2at925?Cwith1mmthicknessunderair/Hegradient.TheTG-DSCprofilesin20mol%CO2/N2andoxygenpermeabilityexperimentswithCO2assweepgasshowthatCGO-YBCOdemonstratesthebestchemicalstabilityagainstCO2,possiblyduetoitsminimumbasicity.ThestableoxygenpermeationfluxofCGO-YBCOunderCO2atmosphererevealsitspotentialapplicationintheoxy-fuelcombustionrouteforCO2capture.
简介:Directconversionoffructose-basedcarbohydratesto5-ethoxymethylfurfural(EMF)catalyzedbyLewisacidinethanolwasinvestigated.ItwasfoundthatBF3(Et)2Owasfavorablefor5-hydroxymethylfurfural(HMF)etherificationtoEMF.BF3(Et)2OcombinationwithAlCl36H2Owiththemolarratioof1wasaneffectivecatalystsystemforsynthesisofEMFfromfructose-basedcarbohydrates.55.0%,45.4%and23.9%ofEMFyieldswereobtainedfromfructose,inulinandsucroseunderoptimizedconditions,respectively.
简介:Amorphouscarbonandgrapheneco-modifiedLiFePO4nanocompositehasbeensynthesizedviaafacilepolyolprocessinconnectionwithafollowingthermaltreatment.Variouscharacterizationtechniques,includingXRD.Mossbauerspectra,Ramanspectra,SEM,TEM,BET,O2-TPO,galvanocharge-discharge,CVandEISwereappliedtoinvestigatethephasecomposition,carboncontent,morphologicalstructureandelectrochemicalperformanceofthesynthesizedsamples.TheeffectofintroducingwayofcarbonsourcesonthepropertiesandperformanceofLiFePO4/C/graphenecompositewaspaidspecialattention.Underoptimizedsyntheticconditions,highlycrystalizedolivine-typeLiFePO4wassuccessfullyobtainedwithelectronconductiveFe2PandFePasthemainimpurityphases.SEMandTEManalysesdemonstratedthegraphenesheetswererandomlydistributedinsidethesampletocreateanopenstructuredLiFePO4withrespecttographene,whiletheglucosederivedcarbonmainlycoatedoverLiFeP04particleswhicheffectivelyconnectedthegraphenesheetsandLiFePO4particlestoresultinamoreefficientchargetransferprocess.Asaresult,favorableelectrochemicalperformancewasachieved.Theperformanceoftheamorphouscarbon-grapheneco-modifiedLiFePO4wasfurtherprogressivelyimproveduponcyclinginthefirst200cyclestoreachareversiblespecificcapacityashighas97mAh·g-1at10Crate.
简介:LiMn2O4andLiNixAlyMn2-x-yO4(x=0.50;y=0.05-0.50)powdershavebeensynthesizedviafacilesolgelmethodusingBehenicacidasactivecheiatingagent.Thesynthesizedsamplesaresubjectedtophysicalcharacterizationssuchasthermogravimetricanalysis(TG/DTA),X-raydiffraction(XRD),Fouriertransforminfraredspectroscopy(FT-IR),field-emissionscanningelectronmicroscopy(FESEM),transmissionelectronmicroscopy(TEM)andelectrochemicalstudiesviz.,galvanostaticcyclingproperties,electrochemicalimpedancespectroscopy(EIS)anddifferentialcapacitycurves(dQ/dE).FingerprintXRDpatternsofLiMn2O4andLiNixAlyMn2-x-yO4fortifythehighdegreeofcrystallinitywithbetterphasepurity.FESEMimagesoftheundopedpristinespinelillustrateuniformsphericalgrainssurfacemorphologywithanaverageparticlesizeof0.5μmwhileNidopedparticlesdepictthesphericalgrainsgrowth(50nm)withice-cubesurfacemorphology.TEMimagesofthespinelLiMn2O4showstheuniformsphericalmorphologywithparticlesizeof(100nm)whilelowlevelofAl-dopingspinel(LiNio.5Alo.05Mn1.45O4)displayingcloudyparticleswithagglomeratedparticlesof(50nm).TheLiMn2O4samplescalcinedat850℃deliverthedischargecapacityof130mAh/ginthefirstcyclecorrespondsto94%coiumbicefficiencywithcapacityfadeof1.5mAh/g/cycleovertheinvestigated10cycles.Amongallfourdopantcompositionsinvestigated,LiNi0.5Al0.05Mn1.45O4deliversthemaximumdischargecapacityof126mAh/gduringthefirstcycleandshowsthestablecyclingperformancewithlowcapacityfadeof1mAh/g/cycle(capacityretentionof92%)overtheinvestigated10cycles.ElectrochemicalimpedancestudiesofspinelLiMn2O4andLiNi0.5Al0.05Mn1.45O4depictthehighandlowrealpolarizationof1562and1100Ω.
简介:Nanostructuredγ-Al2O3withhighsurfaceareaandmesoporousstructurewassynthesizedbysol-gelmethodandemployedascatalystsupportfornickelcatalystsinmethanereformingwithcarbondioxide.ThepreparedsampleswerecharacterizedbyXRD,N2adsorption-desorption,TPR,TPO,TPH,NH3-TPDandSEMtechniques.TheBETanalysisshowedahighsurfaceareaof204m2g-1andanarrowpore-sizedistributioncenteredatadiameterof5.5nmforcatalystsupport.TheBETresultsrevealedthatadditionoflanthanumoxidetoaluminumoxidedecreasedthespecificsurfacearea.Inaddition,TPRresultsshowedthatadditionoflanthanumoxideincreasedthereducibilityofnickelcatalyst.Thecatalyticevaluationresultsshowedanincreaseinmethaneconversionwithincreasinglanthanumoxideto3mol%andfurtherincreaseinlanthanumcontentdecreasedthecatalyticactivity.TPOanalysisrevealedthatthecokedepositiondecreasedwithincreasinglanthanumoxideto3mol%.SEMandTPHanalysesconfirmedtheformationofwhiskertypecarbonoverthespentcatalysts.AdditionofsteamandO2todryreformingfeedincreasedthemethaneconversionandledtocarbonfreeoperationincombinedprocesses.
简介:QuantumdynamicscalculationsforthetitlereactionH(2S)+S2(X3-Σg)→SH(X2Π)+S(3P)areperformedbyusingagloballyaccuratedoublemany-bodyexpansionpotentialenergysurface[J.Phys.Chem.A1155274(2011)].TheChebyshevrealwavepacketpropagationmethodisemployedtoobtainthedynamicalinformation,suchasreactionprobability,initialstate-specifiedintegralcrosssection,andthermalrateconstant.Itisfoundnotonlythatthereisareactionthresholdnear0.7eVinbothreactionprobabilitiesandintegralcrosssectioncurves,butalsothatboththeprobabilityandcrosssectionincreasefirstlyandthendecreaseasthecollisionenergyincreases.Theexistenceoftheresonancestructureinboththeprobabilityandcrosssectioncurvesisascribedtothedeeppotentialwell.Thecalculationoftherateconstantrevealsthatthereactionoccurringonthepotentialenergysurfaceoftheground-stateHS2isslowtotakeplace.
简介:我们在Mn50Ni40SnSbx(x=1,2,3,和4)合金。所有准备样品在房间温度与空间组一起展出B2类型结构。Sb的替换增加原子价电子集中并且减少联合起来的房间体积。作为结果,当x增加,magnetostructural转变向更高的温度很快变。在在不同磁场变化下面的磁性的熵的变化在这转变附近被探索。等温的磁化曲线展出典型metamagnetic行为,显示magnetostructural转变能被一个磁场导致。悦耳的martensitic转变和磁性的熵变化建议那Mn50Ni40SnSbx合金是应用在的吸引人的候选人固态制冷。
简介:Uptothisdate,researchersarestillfacingdifficultiestoexpandthetechnologyofdirectmethanolfuelcells(DMFCs)becauseofthehighoverpotentialrequiredtooxidizethemethanolanditsrelativelypoorperformanceduetoCOpoisoningoftheleading-highcostanodecatalyst.Inlinewiththis,wehavesuccessfullymodifiedthemorphologicalstructureandcompositionoflowcostcobaltbased-metaloxides,MCo2O4(M=ZnandNi),withthesimpleandnobleuseofpolyvinylpyrrolidone(PVP)asgrowthmodifierandsurfacestabilizerduringthesynthesisofnanoparticlesinourpreviousreports,whichshownhighelectrocatalyticactivityandstrongstability.DuetothegoodperformanceofourPVPmodifiedMCo2O4towardspseudocapacitorandoxygenevolutionreactionapplications,wedecidedtoextendourresearchstudytomethanoloxidationreaction.Remarkably,PVPmodifiedNiCo2O4electrodedirectlygrownonnickelfoamsubstrateviaasimplehydrothermalprocessexhibitedbetterperformancecomparedwithPVPmodifiedZnCo2O4andNiCo2O4withoutPVP.Ithadobtainedaremarkablylowonsetpotentialof0.285Vandhighcurrentdensityof280mAcm-2,andshowngreatstabilityandhighpoisontoleranceduringacontinuousCVcyclingandChronoamperometrytest,whichattainedhighefficiencyof86.86%and98.52%,respectively.ThesepositiveresultsofPVPmodifiedNiCo2O4electrodetowardsMORmightbeattributedtoitshierarchical3Dnanostructureswithhighlymesoporoussurfaceandlargesurfaceareawhichmayhaveprovidednumerouselectroactivesites,andtheexceptionalcorrosionstabilityofNiCo2O4electrodeinalkalinesolution.