简介:Theneedformoreactiveandhydrothermallystablefluidcatalyticcracking(FCC)catalyststocombattheeffectofmetalcontaminantshasledtoanincreaseindemandforrareearthoxides.RareearthoxidesenhancecatalystactivityandpreventthelossofacidsitesduringtheFCCunitoperation,especiallywhenheavyresiduewithhighmetalcontentisusedasfeed.Inthispaper,areviewwascarriedouttoshowtheeffectsofrareearthelementsonthestructure,activity,andstabilityofFCCcatalysts.Also,theuseofrareearthelementsasvanadiumtrapswasanalyzedinconjunctionwiththemechanismofcatalystdeactivationbyvanadium.TheobjectivewastoelucidatetheinteractionofvanadiumspecieswiththezeolitecomponentoftheFCCcatalystsandtheroleofrareearthelementsincounteringthedeleteriouseffectsofvanadiumontheFCCcatalysts.
简介:ApplicationoftheEu3+IonforSiteSymmetryDeterminationBinnemansK,Gorller-WalrandC(UniversityofLeuven,DepartmentofChemistry,Co?..
简介:Nd:钇铝柘榴石先锋粉末被同类的降水,和Nd综合:钇铝柘榴石透明陶艺被真空sintering为5h在1700°C作好准备。陶器的材料被轻发射度和地排放枪环境扫描显微镜描绘。用统计和立方米科学理论,学习在在轻发射度和立体声之间的量的关系上被执行在三维的欧几里德几何学的空格的逻辑参数。这被发现Nd的发射度:有在厚度的1公里的钇铝柘榴石分别地在可见、在红外线附近的波长是大约45%和58%。发射度线性地与增加相等的范围直径增加并且当相等的范围直径是20μm时,到达单个水晶的理论价值。有每统一谷物和分离谷物的体积增加吝啬的特定的区域的发射度减少,和有增加的发射度减少在Nd意味着谷物的免费距离:钇铝柘榴石陶艺。
简介:AnovelTb(III)ternarycomplexTb(p-BBA)_3MAAwassynthesizedwith4-benzoylbenzoicacid(p-BBA)andmethacrylicacid(MAA)asligands.ThecomplexwascharacterizedbyIR,UV-visible,thermogravimetricanalysisandfluorescencespectroscopy.Monitoredat544nm,thecomplexdisplayedwideandstrongexcitationbandat300–400nm,whichmatchedwellwiththe365nm-emittingUVchip.Thecomplexexhibitedexcellentgreenemissionat544nm(~5D_4→~7F_5transitionofTb~(3+))underanexcitationat365nm.Besides,thecomplexshowedhighthermalstability.Itsintramolecularenergytransferprocesswasfurtherdiscussed.Furthermore,thecomplexalsohadhigherfluorescencelifetime(1.38ms)andhigherquantumyield(0.372).Finally,electroluminescentpropertiesindicatedthatwhenusedtofabricateLEDwith365nmUVchip(powerefficiencyis18.6lm/W),thecomplexremaineditsfavorableopticalperformance.TheseresultsimpliedthatTb(p-BBA)_3MAAcouldbeusedasagreenphosphorforNUV-basedwhiteLED.
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.