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:Er3+/Yb3+codopedzincateBaGd2ZnO5phosphorsweresynthesizedviaatraditionalsolidstatereaction.ThecrystalstructureandphasepuritywerecheckedbymeansofX-raydiffraction(XRD),andtheresultsshowedthatpurephaseBaGd2ZnO5phosphorswithvariousEr3+,Yb3+concentrationswereobtained.TheinfluenceofEr3+andYb3+dopingconcentrationsonthegreenandredupconversionemissionswasstudied.Itwasfoundthatbothgreenandredupconversionemissionsunder980nmexcitationweretwo-photonprocessesindependentfromtherareearthdopingconcentrations.However,theupconversionluminescenceintensitiesgreatlydependedontherareearthdopingconcentration.Furthermore,thepopulationprocessesofupconversionluminescenceandthequenchingmechanismswereanalyzed.Thetemperature-dependentgreenupconversionluminescencewasstudied,andthetemperaturequenchingprocessoftwogreenupconversionemissionswasmodeled.Thethermalquenchingprocessesofthegreenupconversionemissionscouldbewellexplainedbythemodelweproposed.
简介:Sr1.995–1.5xGdxSiO4:0.005Eu2+phosphorserieswithx=0–0.08molfornear-ultravioletwhitelight-emittingdiodes(NUVw-LEDs)weresynthesizedviasolid-statereactionmethod.XRDprofilepatternandrefinementresultsdemonstratedthatdopingGd3+ionsresultedinthephasetransformation(β-Sr2SiO4→α’-Sr2SiO4).Thephotoluminescencespectrumofthesamplewithx=0moldisplayedtwoemissionpeakscenteredat470and525nm.Thetwo-peakspectrabecameone-peakspectrawiththeGd3+concentrationincreasing.Actually,thefittingresultsdemonstratedthattheone-peakspectrawerestillcomposedoftwosingleemissionspectra.ThephotoluminescenceintensitywasimprovedandtheCIEchromaticitycoordinateswereadjustedviadopingGd3+.