简介:Whitelight-emittingYVO_4:1mol.%Dy~(3+),xmol.%Eu~(3+)phosphorpowderswithordermorphologyandwellcrystallizationwerehydrothermallysynthesizedat180°C.Themicrostructure,white-lightemission,andlight-emittingmechanismofthepowderswerecarefullystudiedusingX-raydiffractometry,scanningelectronmicroscopyandphotoluminescencespectra.TheexcitationandemissionspectraofthephosphorpowdersindicatedthecoexistenceofefficientenergytransferfromEu~(3+)toDy~(3+)andinefficientenergytransferfromDy~(3+)toEu~(3+)besidestheenergytransferfromVO_4~(3–)toEu~(3+).IncreasingtheEu~(~(3+))concentrationinitiallyenhancedandthenweakenedtheluminescentintensityofDy~(3+).Thewhite-lightemissionsofYVO_4:1mol.%Dy~(3+),xmol.%Eu~(3+)phosphorpowderswerebothrelatedtotheenergytransferbetweenVO_4~(3–)andDy~(3+)/Eu~(3+),aswellasbetweenEu~(3+)andDy~(3+).TheinefficientenergytransferfromDy~(3+)toEu~(3+)wasfirstfound.
简介:Eu-activatedCaMoO4phosphorswereco-precipitatedinanaqueoussolution,andNH3·H2O,NH4HCO3and(NH2)2COaspre-cipitatingaidagentswerecomparedbasedonthemorphologyandparticlesizedistributionofthephosphorsamples.Sm3+assensitizerionwasinvestigatedontheluminescenceofCaMoO4:Eu,anditcouldstrengthenthe406nmabsorptionofthisphosphor.Atlast,thescheeliteCaMoO4:EuandwolframiteZnMoO4:Euwereselectedtocomparetheirhostabsorption.TheresultshowedthatthescheelitemolybdatehostexhibitedstrongerUVabsorptionthanwolframiteone.
简介:Thecoilingtemperatureofthehotstriprollingprocessplaysanimportantroleinstripqualitycontrol.Thenewly-builtlaminarflowcoolingcontrolsystemwasindependentlydevelopedbyBaosteel.L2conductstotallydynamiccontrol(L1onlyexecutestheresultfromL2,anddoesnotconductanydynamiccontrol).Thesystemhasmanyadvantages,suchasquickreal-timecontrol,accuratemodelcalculation,quickresponseafterself-adaptation,etc.Comparedwiththe2050mmhotstriprollingline,thenewsystemcansatisfythestrictcoolingrequirementsofhighstrengthsteel,siliconsteelandheavyplatesbecauseofitsnewly-developedtechnologiesofcoolingratecontrol,stripcoolingbysectionsandproportion-integral-differentialcoefficient(PID)feedbackfuzzycontrol.
简介:AseriesofMn-basedcatalysts,MnOx,MnOx-CeO2,Pd-Mn-Ce,MnOx/ACwereprepared.AndtheirperformancesforNOlow-temperatureSCRwereinvestigatedinthisstudy.TheNOconversionisabout90%at100℃onMnOx-CeO2andalmostallNOcanbeconvertedat120℃.SimilarresultsarealsoobservedinthetestsonMnOx-CeO2/AC.Theexcellentlow-temperaturecatalyticactivityofmodifiedMn-basedcatalysts,whichmaybemainlyduetotheoxygenstoragefunctionofCeO2,canimprovetheoxygenflowonthecatalystssurface.ThentheoxidationofNOtoNO2isaccelerated,whichisthekeystepofNOSCR.
简介:ThedopedZnOnanorodsasaphotocatalystwithdifferentEucontentswerepreparedbymicrowaveassistedmethodandtheywerecharacterizedbymeansofX-raydiffraction(XRD),energy-dispersiveX-rayspectroscopy(EDS),UV-Visspectroscopy,surfaceareaBrunauer-Emmett-Teller(BET),X-rayphotoelectronspectroscopy(XPS),scanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM).TheaveragecrystallitesizeandbandgapenergyofEu-dopedZnOwerevariedwiththeEucontent.TheXRDpatternofEu-dopedZnOindicatedhexagonalcrystalstructurewithanaveragecrystallitesizeof25nm.ThepresenceofeuropiumwithtrivalentstateanditsdopingsuccessfullyintothecrystallatticeofZnOmatrixwereconfirmedbyXPStechnique.ThephotocatalyticactivityofEu-dopedZnOnanorodswasevaluatedformethylorangedegradation.Thephotocatalyticexperimentsshowed~91%degradationofmethylorangeover0.2mol.%EudopedZnOsamplewithin3hunderUVlight(365nm).
简介:
简介:NanosizedBaCeo.95Yo.o5O3-δpowderswiththehomogeneouscompositionweresynthesizedbyanewcombustionprocessbasedonthePechinimethod.Apolymericprecursorsolwasformedbyuseofcitricacidandethyleneglycolasthechelatingagentsofmetalions.Theperovskite-typeBaCeo.95Yo.o5O3-δpowderswithuniformshapeandsmallerthan40nminsizedwereobtainedthroughthecombustionofthepolymericprecursorsolattheexistenceofnitricacidandammoniumhydroxide.Itwasfoundtheparticlesizecouldbecontrolledbymodulatingthequantitiesofnitricacidandammoniumhydroxide,thequantitiesoftheresidue,carbonateionswerealsoaffectedbythequantitiesofthecitricacidandethyleneglycol.
简介:YbF2.357,YbF3,Ba2YbF7,andBa2upconversionnanocrystalsdopedwithemitterEr3+ionweresynthesizedinthesamesolventsystemjustwithchangingthemolarratioofBa2+toYb3+intheprecursor,whichcorresponedtothecrystalphasesofrhombohedral,orthorhombic,tetragonal,andcubic,respectively.Allthesamplesemittedboth660nmredlightand543/523nmgreenlightwhichoriginatedfromEr3+-4fnelectronictransitions4F9/2-4I15/2and4S3/2/2H11/2-4I15/2,respectively.ItwasworthmentioningthatYbF3:Er3+,Ba2YbF7:Er3+,andBaF2:Er3+couldemitdazzlinglybrightlightevenundertheexcitationofa980nmCWlaserwithoutputpowerof0.1W.Upconversionemissionmechanismanalysisindicatedthattheintensityratioofredtogreenlighthighlydependedonthesynergisticeffectofcrystalstructure,concentrationquenching,andparticlesize,butwerenotsensitivetocrystallinityaspreviouslyreportedforNaLnF4(Ln=lanthanide).
简介:
简介:氪、氙是空气中的稀有气体,由于具有一定的特性,使氪、氙应用前景广泛,空分中存在多种稀有气体,其中氪、氙含量最少,由于提取工艺复杂,价位高昂,俗称"黄金气体",空分中的氪、氙主要在液氧中,通常伴随产品氧气或液氧排出而被带走,随着空分设备日益大型化,提取氪、氙的原料气液氧产能增加,从液氧中提取氪、氙蕴藏着巨大经济前景。
简介:SmOHCO3micro/nanoparticleswerepreparedinwater/oil(W/O)reversemicroemulsioncomposedofcetyltrimethylammoniumbromide(CTAB),n-octane,n-butanol,Sm(NO3)3·6H2Oandureaaqueoussolutionbythecouplingrouteofhomogeneousprecipitationwithmicroemulsion.ThenanoparticleswerecharacterizedandanalyzedbyX-raypowderdiffraction(XRD),thermalgravimetricanddifferentialthermalgravimetricanalysis(TG-DTG),Fouriertransforminfraredabsorptionspectra(FT-IR)andscanningelectronmicroscope(SEM).TheresultsshowedthatthephaseSmOHCO3micro/nanoparticleswasinagreementwithpureorthorhombicphase.ThedifferentmorphologiesofSmOHCO3micro/nanoparticleswithgoodmonodispersityandsizewereobtainedbyregulatingthereactiontemperatureandreactiontime.PossibleformationmechanismsofthemorphologicalstructureofSmOHCO3wereproposedanddiscussed.