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:水体重金属污染较难处理,且会对水生物造成严重的影响。为探讨水体中重金属对藻类的毒性影响,以普通小球藻(Chlorellavulgaris)和铬(Cr^3+)为材料,研究不同浓度Cr^3+对普通小球藻生理、生化特性的影响,检测不同浓度的Cr^3+对小球藻的毒性效应。结果表明,小球藻的最优生长温度为31℃。此条件下,Cr^3+浓度为3mg·L^-1时,小球藻的生物量最大。Cr^3+的浓度低于3mg·L^-1时,Cr^3+能促进小球藻的生长,且藻细胞中光合色素、蛋白质、可溶性糖、丙二醛(MDA)的含量及超氧化物歧化酶(SOD)的活性也逐渐增加。当各胁迫组的Cr^3+浓度超过3mg·L^-1时,随着Cr^3+浓度的提高,C.vulgaris的生长受到明显的抑制,藻细胞的光合色素、蛋白质和可溶性糖含量呈现逐渐下降的趋势,而MDA含量持续增加,SOD和脯氨酸则表现出先持续增高后降低(Cr^3+浓度为7mg·L^-1时)的趋势。证明不同浓度的Cr^3+对小球藻的生理生化特性有不同程度的毒性效应。
简介:Forenhancingthe2.0μmbandfluorescenceofHo3+,acertainamountofWO3oxidewasintroducedintoHo3+/Tm3+/Yb3+tri-dopedtelluriteglasspreparedusingmelt-quenchingtechnique.Thepreparedtri-dopedtelluriteglasswascharacterizedbytheabsorptionspectra,fluorescenceemissionandRamanscatteringspectra,togetherwiththestimulatedabsorption,emissioncross-sectionsandgaincoefficient.TheresearchresultsshowthattheintroductionofWO3oxidecanfurtherimprovethe2.0μmbandfluorescenceemissionthroughtheenhancedphonon-assistedenergytransfersbetweenHo3+/Tm3+/Yb3+ionsundertheexcitationof980nmlaserdiode(LD).Meanwhile,themaximumgaincoefficientofHo3+at2.0μmbandreachesabout2.36cm-1.Anintense2.0μmfluorescenceemissioncanberealized.
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:Layereddoublehydroxides(LDHs)withhydrotalcite-typestructurecontainingFe3+,Al3+andMg2+werepreparedbymeansofacoprecipitationmethod.Theproductswerecharacterizedbyelementanalysis,X-raypowderdiffractionandtransmissionelectronmicroscopy.Itwasfoundthatevenifthemolarratioofn(Fe+Al)/n(Fe+Al+Mg)>0.33,yetapurehydrotalcite-likecompound(HTlc)phasewasgainedwhenn(Fe)/n(Al+Mg+Fe)≤0.30andn(Al)/n(Al+Mg+Fe)≤0.30;theAl(OH)3phaseappearedintheproductswhenn(Al)/n(Al+Mg+Fe)>0.30;andanamorphousphaseemergedwhenn(Fe)/n(Al+Mg+Fe)>0.33.TheseresultsshowthatthereisnoconcentrationsuperpositioneffectbetweenFe3+andAl3+onthecrystallinestateoftheproducedsamples.Inourpreviouswork,theconcentrationsuperpositioneffectbetweenZn2+andMg2+inthesynthesisofZn-Mg-Al-LDHswasfound.ForthepreparedFe-Al-Mg-LDHssamples,thevalueoflatticeparameteraisbetween0.30-0.32nm;andthevalueoflatticeparametercisbetween2.30-2.47nm,thebasalspacingisintherangeof0.76-0.83nm.Whentheratioofn(Fe)/n(Al)isaconstant,thevaluesofaandcincreasewiththeincreaseoftheMg2+contentoftheproducedsamples.Themeanparticlesizeandthemeancrystalgrainweredeterminedbyvirtueofaparticle-sizeinstrument,XRD-ScherrerformulaandTEMmethod,respectively.
简介:采用高温固相法制备Ba3Gd(BO3)3:Eu^3+,Tb^3+荧光粉,通过X射线衍射(XRD)和光致发光光谱分别对其物相和发光性能进行表征,并研究Tb^3+离子掺杂量对其发光性能的影响。结果表明:Eu^3+和Tb^3+均作为发光中心进入到Ba3Gd(BO3)3的晶格中并取代Gd^3+的格位;在378nm激发下,样品表现出Eu^3+和Tb^3+的特征跃迁,分别发射红光和绿光;随着Tb^3+掺杂量的增加,Tb^3+的绿色发射强度先增强后减弱,说明存在浓度猝灭,而Eu^3+的红色发射强度逐渐提高,说明Tb^3+对Eu^3+有敏化作用;样品Ba3Gd(BO3)3:Eu^3+,Tb^3+的发光颜色可从绿色调整到橙红色。
简介:Er~(3+)andLa~(3+)codopedY_2O_3nanocrystallinepowdersweresynthesizedbygelcombustionmethodandcharacterizedwiththermalanalysis,X-raydiffraction(XRD),transmissionelectronmicroscopy(TEM),high-resolutionTEM(HRTEM)techniquesandfluorescencespectroscopy.Afterbeingcalcinedat1200oC,the(Y_(1–x)La_x)_2O_3:Er~(3+)powderswereconfirmedtobecubicY_2O_3phasewiththecrystallinegrainsizeintherangeof20–40nm.TheEr~(3+)emissionat1.53μmfromthe~4I_(13/2)→~4I_(15/2)transitionwasobserved,whichwasfoundtobeenhancedbyintroducingLa~(3+)ions.SuchenhancementcouldbeattributedtotheadjustmentofEr~(3+)ions'localenvironmentbythecodopingofLa~(3+)ions,leadingtotheincreasedgroundstateabsorptioncrosssectionofEr~(3+)ions.
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:Erbium,Ytterbium-codopedZrO2nanoparticles(ZrO2∶Er3+,Yb3+)werepreparedbythesol-emulsion-geltechnique.Thepurposeofthepresentstudyistheapplicationofupconversionphosphorinthebiologicallabel.Inordertomakeoutthemechanismofupconversionunder980nmexcitationthe488nmpumpwasused.Theinfluenceoftemperatureonthecrystallitephasewasstudied.TheresultsconfirmtheupconvertedmechanisminZrO2∶Er3+,Yb3+nanocrystalsisduetoanenergytransferupconversion(ETU).
简介:Er3+/Yb3+codopedzincateBaGd2ZnO5phosphorsweresynthesizedviaatraditionalsolidstatereaction.ThecrystalstructureandphasepuritywerecheckedbymeansofX-raydiffraction(XRD),andtheresultsshowedthatpurephaseBaGd2ZnO5phosphorswithvariousEr3+,Yb3+concentrationswereobtained.TheinfluenceofEr3+andYb3+dopingconcentrationsonthegreenandredupconversionemissionswasstudied.Itwasfoundthatbothgreenandredupconversionemissionsunder980nmexcitationweretwo-photonprocessesindependentfromtherareearthdopingconcentrations.However,theupconversionluminescenceintensitiesgreatlydependedontherareearthdopingconcentration.Furthermore,thepopulationprocessesofupconversionluminescenceandthequenchingmechanismswereanalyzed.Thetemperature-dependentgreenupconversionluminescencewasstudied,andthetemperaturequenchingprocessoftwogreenupconversionemissionswasmodeled.Thethermalquenchingprocessesofthegreenupconversionemissionscouldbewellexplainedbythemodelweproposed.
简介:Cr的Nanopowder:Cr的GGG和nanopowder,Nd:有从0.1at.%到1.5at.%的Cr3+的不同集中的GGG被大音阶的第五音胶化方法用醋酸和乙烯乙二醇综合。热gravimetric分析和微分扫描热量测定(TGA-DSC),X光检查衍射(XRD)和光致发光光谱学被用来描绘粉末。当在1000点对待时,雏晶尺寸是大约58nm?????????????????猯灵?匠?猼'T资???猼灵?????????猯'T??猼灵???? ̄?????猯'T????猯灵??猼'T?????吗????????????????‵渠????????浮??