简介:Ca-dopedBaMgAl10O17:Eu2+,Mn2+(BAM)bluephosphorsweresynthesizedbyfluxassistedsolid-statereactionmethodusingCaF2andBaF2asco-flux.GooddispersityandparticlesizehomogenizationofhexagonalpurephaseBAMwereobtainedbysinteringat1400℃.TheeffectsoftheCa2+ionscontentonthestructure,morphologyandphotoluminescencepropertiesofthephosphorswerestudied.TheresultsindicatedthattheincorporationofCacoulddecreasethelatticeconstant,improvethehomogeneityanddispersityandenhancethephotoluminescence(PL)intensityofthephosphoreffectively.TheoptimumBa0.86Ca0.04Mg0.97Al10O17:0.1Eu2+,0.03Mn2+PLintensitywasenhancedforabout30%andrelativebrightnesswasimprovedabout4%.Furthermore,thesynthesizedBAMandcommercialBAMphosphorswereannealedfor30minat600oCinair.TheCa-dopedphosphorshadstrongeremissionintensity,higherbrightnessandbetterchromaticitystabilitythanthatofthecommercialphosphor.TheseresultsindicatedthatCa-dopedbluephosphorshadgoodpotentialapplicationsinthecommercialtricolorfluorescentlampsaswellasinotherdisplayandlamps.
简介:AseriesofCe0.5Fe0.30Zr0.20O2catalystswerepreparedbydifferentmethods(co-precipitationsmethod,citricacidsol-gelmethod,impregnationmethod,physicalmixedmethod,andhydrothermalmethod)andcharacterizedbyX-raydiffraction(XRD),Ramanspectroscopy,Brunauer-Emmett-Teller(BET)andH2-TPRmeasurements.Potentialofthecatalystsinthesootoxidationwasevaluatedinatemperature-programmedoxidation(TPO)apparatus.TheresultsshowedthatalltheFe3+andZr4+wereincorporatedintocerialatticetoformapureCe-Fe-Zr-Osolidsolutionfortheco-precipitationsample,buttwokindsofFephasesexistedintheCe-Fe-Zr-Ocatalystspreparedbyothermethods:Fe3+incorporatedintoCeO2latticeanddispersedFe2O3clusters.ThefreeFe2O3clusterscouldimprovetheactivityofcatalystsforsootoxidationcomparingwiththepureCe-Fe-Zr-OsolidsolutionowingtothesynergeticeffectbetweenfreeFe2O3andsurfaceoxygenvacancies.Inaddition,theactivityofcatalystsstronglyreliedonthesurfacereducibilityoffreeFe2O3particles.HoldingbothabundantfreeFe2O3particlesandhighoxygenvacancyconcentration,thehydrothermalCe0.5Fe0.3Zr0.2O2catalystpresentedthelowestTi(251°C,ignitiontemperatureofsootoxidation)andTm(310°C,maximumoxidationratetemperature)forsootcombustion(withtight-contactbetweensootandcatalysts)amongthefivesamples.Evenafteragingat800°Cfor10h,theTiandTmwerestillrelativelylow,at273and361°C,respectively,indicatinghighcatalyticstability.
简介:Praseodymium(Pr)wasimpregnatedtoCeO2-ZrO2solidsolutionbyanimpregnationmethod.Theas-obtainedPrmodifiedCeO2-ZrO2wasimpregnatedwith1wt.%Pdtopreparethecatalysts.ThestructureandreducibilityofthefreshandhydrothermallyagedcatalystswerecharacterizedbyX-raydiffraction(XRD),Raman,X-rayphotoelectronspectroscopy(XPS),COchemisorptionandH2temperature-programmedreduction(H2-TPR).Theoxygenstoragecapacity(OSC)wasevaluatedwithCOservingasprobegas.EffectsofimpregnatedPronthestructureandoxygenstoragecapacityofcatalystswereinvestigated.TheresultsshowedthattheagedPr-impregnatedsampleshadmuchhigherOSCandbetterreducibilitythantheunmodifiedones.TheschemeofstructuralevolutionsofthecatalystswithandwithoutPrwasalsoestablished.PartialoftheimpregnatedPrdiffusedintothebulkofCeO2-ZrO2duringageing,whichinhibitedthesintering,andincreasedtheamountofoxygenvacanciesinCeO2-ZrO2support.Furthermore,thoseimpregnatedPrspecieswhichcoveredonthesurfaceofthesupportobstructedthestrongmetal-supportinteractionbetweenPdandCesoastoreducetheencapsulationofPdaswellasthebackspill-overoftheoxygenduringthecatalyticprocess.
简介:通过金相显微镜(OM)、扫描电镜(SEM)和动态热机械分析仪(DMAQ800)等分析手段研究粉末冶金法制备的Ti-47Al-2Cr-2Nb-0.2W(原子分数,%)合金微观组织对其阻尼性能的影响。研究结果表明:Ti-47Al-2Cr-2Nb-0.2W合金初始组织为近γ组织,其阻尼性能最差,在振幅为100μm时,损耗因子仅为0.007;在1330℃下保温15min空冷可获得细小全层片组织,层片晶团的平均尺寸约为200μm,其损耗因子在振幅为100μm时达到0.012。随温度升高或保温时间延长,层片尺寸和晶团尺寸明显增大,合金阻尼性能下降,保温120min时层片晶团的平均尺寸约为510μm,其损耗因子在振幅为100μm时为0.009。细小全层片的阻尼性能最好,而双态组织的阻尼性能介于近γ组织和细小全层片组织之间。
简介:混合氧化物(Ce0.6Zr0.4O2)由帮助微波的加热一起沉淀准备了的CeO2-ZrO2被用作支持经由早期湿的受精的方法与各种各样的CuO内容(0wt.%15wt.%)准备一系列CuO/Ce0.6Zr0.4O2催化剂。获得的CuO/Ce0.6Zr0.4O2样品被N2吸附,XRD,拉曼,TEM和H2-TPR技术,和他们的催化活动描绘因为公司氧化被调查。结果证明CuO/Ce0.6Zr0.4O2催化剂的活动被CuO的内容强烈影响,并且有10wt.%CuO的催化剂在公司氧化展出了最好的催化活动,它能在催化剂被归因于CuO,和高氧空缺集中的高分散和reducibility。
简介:Eu2+andDy3+codoped(Ca,Sr)7(SiO3)6Cl2yellowphosphorsweresuccessfullysynthesizedbyself-fluxmethod.Thestructure,morphologyandphotoluminescencepropertieswereinvestigatedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andphotoluminescencespectra.Theas-preparedphosphorshowedabroademissionspectrumcenteredat550nmforEu2+single-dopedphosphor,whilelocatedat548–544nmfortheEu2+,Dy3+codopedsamplesunderexcitationat380nmlight.TheemissionintensitywasgreatlyimprovedwhenDy3+wasdopedintothe(Ca,Sr)7(SiO3)6Cl2:Eu2+system.Thecomposition-optimizedsamplewith3mol.%ofDy3+andconstant10mol.%ofEu2+exhibiteda220%PLenhancementcomparedtothephosphorwith10mol.%Eu2+single-doped.Meanwhile,itwasfoundthatthequantumefficiencyofphosphornamely(Ca,Sr)7(SiO3)6Cl2:3mol.%Dy3+,10mol.%Eu2+couldgetupto24.6%.Thesynthesizedyellow-emitting(Ca,Sr)7(SiO3)6Cl2:Dy3+,Eu2+isapromisingcandidateashigh-efficiencyyellowphosphorforNUV-excitedwhiteLEDs.
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.