简介:LanthanidedopedNaYF4microcrystalsweresynthesizedviaafacilehydrothermalmethod.MulticolorupconversionluminescencewasobservedinNaYF4microcrystalsdopedwithYb3+/Er3+,Yb3+/Tm3+,andYb3+/Er3+/Tm3+undertheexcitationof980nminfraredlight.Importantly,theexcitationpowerdensitydependenceofupconversionemissionintensityindicatedclearlytheenergytransferfromTm3+toEr3+ionsundertheexcitationoflowpowerdensity(5×102–9×102W/cm2).Meanwhile,theinverseenergytransferfromEr3+toTm3+ionsundertheexcitationofrelativelyhigherpowerdensity(4.1×104–4.9×104W/cm2)wasalsorevealed.ThiswasadirectevidenceforreversibleenergytransferbetweenEr3+andTm3+ions.Undertheexcitationofhighpowerdensity(4.1×104–4.9×104W/cm2),darksensitizerswerealsomotivatedsothatthebottleneckeffectofhighconcentrationYb3+iondopingwasbroken.ThiswasthemainreasonforrealizinghighupconversionefficiencyofthesampleswithheavydopingofYb3+ion.
简介:Redphosphor(Y,Gd)BO3:Eu3+withgrainshape,smallsize,non-agglomerate,highcrystallinityandgoodphotoluminescence(PL)intensitywaspreparedbyacomplexmethodthattheprecursorofthephosphorwaspreparedbyco-precipitationmethodandthephosphorwaspreparedbycombustionmethod.TheSEMphotosandthephotoluminescencespectrumexcitedunderVUVshowthatthemorphologyandluminescentpropertiesofthisphosphoraresatisfiedwhenanappropriateamountofureawasadoptedasthecombustionagentinthepreparationprocedure.
简介:TheelectrodeprocessofY3+iononmolybdenumandnickelelectrodeshasbeenstudiedbycyclicvoltammetryandchronopotentiometryintheYCl3-NaCl-KClmelt.Theoverallchargetransferprocessisatwo-stepreaction:Y3++e=Y2+;Y2++2e=Y.YttriumreducedonthenickelelectrodecanformaseriesofNi-Yalloys.X-raydiffractionanalysiswasemployedtodeterminethealloycompositionsformedunderdifferentcon-ditions.
简介:ThephotocatalystsK4Nb6017andK4Nb6017dopedwithFe^3+andCr^3+werepreparedbysolidstatereactionandwerecharacterizedbypowderx-raydiffraction,UV-visdiffusivereflectanceandscanningelectronmicroscopy.ThephotocatalyticactivityofK4Nb6O17andK4Nb6O17dopedwithFe^3+,Cr^3+wereinvestigatedwithmethanolaselectrondonorandPtaspromotercatalystunder+400nmUVirradiation.Thedifferenceofphotocatalyticactivitybetweenthemwasalsodiscussed.TheindividualrateofhydrogenevolutionfortheK4Nb6O17,Fe-K4Nb6O17andCr-K4Nb6O17asphotocatalystsare5.35,5.00,6.25mmol·L^-1.h^-1respectively.
简介:YPO_4phosphorssingle-dopedwithSb~(3+)orGd~(3+)andco-dopedwithSb~(3+)andGd~(3+)werepreparedbyasolid-statereactionmethod.Thephasepurity,morphology,photoluminescenceexcitationandemissionpropertiesofthepreparedphosphorswereinvestigated.TheresultsshowedthatSb~(3+)couldsensitizeGd~(3+)intheco-dopedphosphorswhichmadethephosphorsexcitablebyshort-waveultraviolet(UV)atawavelengthbetween220and260nm.Under253.7nmexcitation,theco-dopedphosphorsY_(1–x–y)PO_4:Sb~(3+)x,Gd~(3+)yshowedstrongemissionofGd~(3+)atawavelengthof312nmwhoseintensitychangedwiththedopingconcentrationsofGd~(3+)andSb~(3+).TheoptimizedY_(0.77)PO_4:Sb~(3+)0.07,Gd~(3+)0.16phosphorshowedanintensitycomparabletocommercialLaPO_4:Cephosphor(UVB-315),makingitapotentialcandidateformercurylow-pressuredischargenarrow-bandUV-Bemittinglamps.
简介:本文从酒钢3×6000Nm~3/h制氧生产工艺及其控制设备的现状出发,介绍了改造后DCS控制系统软、硬件的构成和实现的主要功能,取得了良好的应用效果。
简介:TheZrO2-Al2O3ceramiccompositeswerepreparedbyappropriatetechniqueswithcommercialZrO2andAl2O3powdersasrawmaterialsandY2O3asstabilizer.TheresultsindicatethatwiththeintroductionofAl2O3intotheZrO2matrixwherethequantityofadditiveY2O3is3.5%(molefraction),thegrowthofZrO2grainsisefficientlyinhibited,whichhelpstheZrO2grainsexistinametastabletetragonalmanner;thushigherstrengthandtoughnessareacquired.Whenthecontentofaluminais20%(massfraction),thebendingstrengthandfracturetoughnessofthecompositesare676.7MPaand10MPa·m1/2respectively,themechanicalbehaviorsareclosetothosepreparedwithZrO2andAl2O3powderssynthesizedthroughwetchemicalapproach.Themechanicalbehaviorsofthecompositesarewellimprovedowingtothedispersiontougheningofaluminagrainsandphasetransformationtougheningofzirconiagrains.
简介:AseriesofCeB6-dopedandCeO2-dopedCa1-xSiAlN3:xCe3+(denotedasCASN:Ce3+@CeB6andCASN:Ce3+@CeO2,respectively)weresynthesizedbyalloy-nitridationmethodunderhigh-puritynitrogenatmosphere.Themorphologies,crystalphases,andluminescencepropertieswereinvestigatedindetail.WithanincreaseintheconcentrationofCeB6,theunitcellvolumeofCASN:Ce3+@CeB6slightlyincreasesduetothesubstitutionbetweenions,whichleadstoachangeofmicrostructurearoundCe3+.CASN:Ce3+@CeB6efficientlyemitsyellow-orangelightwithamaximumemissionintensityataround550nmforthecontentxof0.01(beingincomparablesituation,CASN:Ce3+@CeO2isx=0.04)whenexcitedat460nm.ComparedwithCASN:Ce3+@CeO2,theredemissioncomponentofCe3+inCASN:Ce3+@CeB6ismuchstronger.Thisisascribedtoenergytransferofintra-Ce3+(withinoneCe3+ion)andinter-Ce3+(betweenCe3+andCe3+ions).Inaddition,thereplacementsofN3-(0.132nmforCN=4)andO2-(0.124nmforCN=4)byB2-(0.140nmforCN=4),whichcanleadtoamarkedexpansionofthehostlatticeandadecreaseoftheoxidationofsamples,arealsoresponsiblefortheincreaseofredemissioncomponent.Furthermore,CASN:Ce3+@CeB6phosphorhasanexcellentthermalstabilitybecauseofthepartialsubstitutionofCe-O(Ce-N)bondsbymorecovalentCe-B.Asaresult,theoutstandingluminescentpropertiesofCASN:Ce3+@CeB6phosphormakeitpracticaltouseinthesinglephosphor-coatedhigh-color-renderingpowerwhiteLED.
简介:PolycrystallineNd3+andLa3+co-dopedyttriananopowderNd3+:Y1.90La0.10O3fortransparentceramicswassynthesizedbyco-precipitationmethodusingoxalateacidastheprecipitantand(NH4)2SO4astheelectricalstabilizerunderultrasonicradiation.Nanopowderscalcinedatdifferenttemperatureswerecharacterizedwiththermalgravimetric-differentialthermalanalysis(TG/DTA),X-raydiffraction(XRD),transmittingelectronmicroscopy(TEM),energydispersivespectrometry(EDS)andspectralanalysistechniques.Th...
简介:Ternarycomplexesofeuropiumandterbiumwithbenzoicacidand1,10-phenanthroline[RE(BA)3phen](BA=benzoatephen=1,10-phenanthroline)wereintroducedintoasilicamatrixbysol-gelmethod.Thethermalstabilityandluminescencebehaviorofthecomplexesinsilicagelswerestudiedincomparisonwiththecorrespondingsolid-statecomplexesbythermaldecomposition,excitationandemissionspectra.Thethermalstabilityofthecomplexesisenhancedinsilicagelmatrixandtheluminescenceremainesunchanged.
简介:Er3+/Yb3+codopedzincateBaGd2ZnO5phosphorsweresynthesizedviaatraditionalsolidstatereaction.ThecrystalstructureandphasepuritywerecheckedbymeansofX-raydiffraction(XRD),andtheresultsshowedthatpurephaseBaGd2ZnO5phosphorswithvariousEr3+,Yb3+concentrationswereobtained.TheinfluenceofEr3+andYb3+dopingconcentrationsonthegreenandredupconversionemissionswasstudied.Itwasfoundthatbothgreenandredupconversionemissionsunder980nmexcitationweretwo-photonprocessesindependentfromtherareearthdopingconcentrations.However,theupconversionluminescenceintensitiesgreatlydependedontherareearthdopingconcentration.Furthermore,thepopulationprocessesofupconversionluminescenceandthequenchingmechanismswereanalyzed.Thetemperature-dependentgreenupconversionluminescencewasstudied,andthetemperaturequenchingprocessoftwogreenupconversionemissionswasmodeled.Thethermalquenchingprocessesofthegreenupconversionemissionscouldbewellexplainedbythemodelweproposed.