简介:Aseriesofnovelbluelong-lastingphosphorescencephosphorsSr6Al18Si2O37:Eu2+,RE3+(RE3+=Ho3+,Gd3+,Dy3+andPr3+)werepreparedbytheconventionalhigh-temperaturesolid-statereactioninareductiveatmosphere.TheirpropertiesweresystematicallyinvestigatedutilizingX-raydiffraction(XRD),photoluminescence,phosphorescenceandthermoluminescence(TL)spectra.ThephosphorsemittedbluelightthatwasrelatedtotheemissionofEu2+dueto5d-4ftransition.Brightbluelong-lastingphosphorescence(LLP)couldbeobservedaftertheexcitationsourcewasswitchedoff.Fortheoptimizedsample,thebluelong-lastingphosphorescencecouldlastfornearly4hinthelightperceptionofthedark-adaptedhumaneye(0.32mcd/m2).TheeffectsofRE3+ionsonphosphorescencepropertiesofthephosphorswerestudied,andtheresultsshowedthattheco-dopingofRE3+ionsgreatlyenhancedtheintensityofthepeakaround315Kwhichwasrelatedtothelonglastingphosphorescenceofthephosphorsatroomtemperatureandconsequentlyimprovedtheperformanceofthebluephosphorescencesuchasintensityandpersistenttime.
简介:EffectofCe-Mg-Si(lightRE)andY-Mg-Si(heavyRE)nodulizersonthemicrostructuresandmechanicalpropertiesofheavysectionductileironwasinvestigatedtodevelopthematerialofspent-nuclear-fuelcontainers.Twoas-castsweretreatedbythesamequalitypercentageoflightREandheavyRE,respectively.Fourpositionswerechosentostandfordifferentsolidificationcoolingratesofspecimens.Thetensilestrength,elongationandimpacttoughnessofspecimenstreatedbyheavyREwereallhigherthanthoseofthespecimenstreatedbylightRE.Withthedecreaseofcoolingrate,themechanicalpropertiesoftwospecimensdecreased,andthefracturemorphologychangedfromductilefracturetobrittlefracture.TheimprovingeffectofmechanicalpropertiesbetweenheavyREandlightREwasobviousduetothebetteranti-degradationpropertyofheavyRE.Whilethesolidificationprocesslastedformorethan250min,theimprovingeffectwasnotobviousduetoseriousspheroidalizationdecaying.
简介:NanosizedBaCeo.95Yo.o5O3-δpowderswiththehomogeneouscompositionweresynthesizedbyanewcombustionprocessbasedonthePechinimethod.Apolymericprecursorsolwasformedbyuseofcitricacidandethyleneglycolasthechelatingagentsofmetalions.Theperovskite-typeBaCeo.95Yo.o5O3-δpowderswithuniformshapeandsmallerthan40nminsizedwereobtainedthroughthecombustionofthepolymericprecursorsolattheexistenceofnitricacidandammoniumhydroxide.Itwasfoundtheparticlesizecouldbecontrolledbymodulatingthequantitiesofnitricacidandammoniumhydroxide,thequantitiesoftheresidue,carbonateionswerealsoaffectedbythequantitiesofthecitricacidandethyleneglycol.
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简介:ToevaluatethepossibilityofusingGd-Si-Gealloysinmagneticrefrigerators,samplesofGd-Si-GealloysweremadeofdomesticGd.Themagnetocaloriceffectofsampleswasestimatedbymagneticentropychange(-ΔSm)calculatedfromM-HcurvesaccordingtoMaxwellrelation.ThefirstorderphasetransformationwasdestroyedduetotheimpuritiesinthecommercialGd,sothatnogiantmagnetocaloriceffectwasfound.ThesamplesmadeofpurifiedGdexhibitfirstorderphasetransformation,andthe-ΔSmisbasicallyconsistentwiththepublisheddataofAmeslaboratory,USA.ThisworkprovesthatGd-Si-GealloysmadeofdomesticGdcanbeutilizedinmagneticrefrigerators.
简介:MossbauerEffectofRapidlyQuenchedAl-Fe-V-Si-MmAlloysWangJianqiang(王建强),ChaoYuesheng(晁月盛),ZengMeiguang(曾梅光),ZhangBaojin(张宝金),Ch...
简介:TheZrO2-Al2O3ceramiccompositeswerepreparedbyappropriatetechniqueswithcommercialZrO2andAl2O3powdersasrawmaterialsandY2O3asstabilizer.TheresultsindicatethatwiththeintroductionofAl2O3intotheZrO2matrixwherethequantityofadditiveY2O3is3.5%(molefraction),thegrowthofZrO2grainsisefficientlyinhibited,whichhelpstheZrO2grainsexistinametastabletetragonalmanner;thushigherstrengthandtoughnessareacquired.Whenthecontentofaluminais20%(massfraction),thebendingstrengthandfracturetoughnessofthecompositesare676.7MPaand10MPa·m1/2respectively,themechanicalbehaviorsareclosetothosepreparedwithZrO2andAl2O3powderssynthesizedthroughwetchemicalapproach.Themechanicalbehaviorsofthecompositesarewellimprovedowingtothedispersiontougheningofaluminagrainsandphasetransformationtougheningofzirconiagrains.
简介:Differentrareearth(RE=La,Ce,Pr,Nd,Sm,Y)andCumodifiednickelcatalystsforhydrogenproductionfrommethanedecompositionweresynthesizedbyasol-gelprocessandmethod.ThecatalystswerecharacterizedoranalyzedthroughBrumauer-Emmett-Teller(BET),X-raydiffraction(XRD),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM)techniques.Andthehydrogenproductionperformancewasalsoevaluatedbyafixed-bedandmicro-reactiontechniquewithCH4→C+H2asaprobereaction.Theresultsshowedthatrareearthmodificationhadplayedagreatrolefornickelcatalysts,forexample,smallernickelparticles,goodthermalstability,highactivity,etc.Lawasthebestadditiveamongrareearthmodification.TheSEMofrareearthmodifiedcatalystsshowedorderedflower-likestructureandrareearthmodificationmadethenickelparticlesmovetothesurfaceofcatalysts.Inaddition,theSEMofnano-carbonswasalsochangedbyrareearthmodificationwithlong,narrownano-carbonfibersortubesobtained.Solidcarbonformationwaspreventedbyrareearthmodification.
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