简介:YLiF4:Er3+wassynthesizedbyhydrothermalmethod.ConcentrationofEr3+ischangedfrom0to5%.TheabsorptionofEr3+inallsamplesfrom200to1200nmwasmeasuredatroomtemperature.TheJ-OparameterscalculatedfromabsorptionspectrumareΩ2=1.05×10-20cm2,Ω4=1.25×10-20cm2andΩ6=1.35×10-20cm2.Infrared-to-visibleupconversionemissionofYLiF4:Er3+wasobservedwhenexcitedby980nm.TheresultsshowthattheEr3+contentislessthan1.5%,excite-stateabsorptionisthemainmechanismofupconversionemission.WhenEr3+contentislargerthan1.5%,bothoftheexcite-stateabsorptionandenergytransferleadtotheupconversionluminescence.TheupconversionintensitywasenhancedwiththeincreasingofEr3+concentration.Atroomtemperature,thelifetimeof2H11/2and4S3/2is205μswhilethatof4F9/2is188μsforsampleEr-2.Thetransitionratesandquantumefficiencywerealsocalculated.Thequantumefficienciesof4S3/2and4F9/2are27.9%and10.7%,respectively.
简介:Inthepresentstudy,sampleswereextensivelycollectedthroughoutthestainlesssteelmanufacturingprocess.Thethree-dimensionalmorphologyofinclusionswasrevealedbynon-aqueoussolutionelectrolysis.Thehighconcentrationofaluminuminferrosiliconcausedtheincrementof[Al]sinsteelandAl2O3ininclusions,whichledtothehighermeltingtemperatureofinclusions.ItwasconcludedthattheapplicationoflowAlferrosiliconandcalciumtreatmentcouldpreventtheformationofAl2O3-richinclusions.
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简介:AseriesofLa2O3/MCnylonnanocompositeswerepreparedviainsitupolymerization.Theeffectsofcontentofnano-La2O3onthemechanicalpropertiesofnanocompositeswerestudied.Dispersionofnano-La2O3inMCnylonmatrixwasobservedwithSEM.ThecrystalstructureofnanocompositeswascharacterizedbymeansofXRD.SEManalysisshowsthatLa2O3nanoparticlesareuniformlydispersedinMCnylonmatrixandlittleclusteringexistswhenthecontentofnano-La2O3islowerthan1%,however,whenthecontentofnano-La2O3ismorethan1%,itbeginstocluster.XRDanalysisindicatsthatnano-La2O3doesnotchangethecrystalstructureofMCnylon.Mechanicalpropertiestestsshowthatthetensilestrength,elongationatbreak,impactstrength,flexuralstrength,andflexuralmodulusofnanocompositesfirstincreasethendecreaseasthecontentofnano-La2O3isincreased.Whenthecontentofnano-La2O3is0.5%,thetensilestrengthandelongationatbreakofnanocompositesreachmaximum,whichare17.9%and52.1%higherrespectivelythanthoseofMCnylon.Whenthecontentofnano-La2O3is1.0%,theimpactstrength,flexuralstrengthandflexuralmodulusofnanocompositesreachmaximum,whichare36.6%,12.7%and16.3%higherrespectivelythanthoseofMCnylon.
简介:Inthispaper,varioustechniquesincludingBET,XRD,SEMandXPSwereusedtostudythesinteringofpureandLa2O3-dopedtitania.Theexperimentalresultsshowthatsinteringoftitaniaproceedsviavolumediffu-sion.Addingoflanthanumoxidedecreasestherateofsinteringandhindersthephasetransitionfromanatasetorutilecrystalbystrongsurfaceinteractionbetweenthemixedcrystals(La4Ti9O24,La0.66TiO2.99)andTiO2.
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简介:Sm3+dopedsodalimesilicateglassesco-dopedwithAs2O3werepreparedandcharacterisedbymeasuringtheirabsorptionspectrainUV-VIS/NIRregionsandluminescencespectrainthevisibleregion.Judd-Ofeltintensityparameters,Ωλ,wereevaluatedfromthemeasuredintensifiesofthevariousabsorptionbands.ΩλparametersoftheseglasseswerecomparedwiththeΩλparametersofotherreportedSm3+glassestostudythebondingenvironmentsurroundingtheSm3+inthepresentglasses.Presenceof[AsO4]3-tetrahedrainthesecondcoordinationspherearoundthecentralSm3+ionmadetheseglasseslesscovalentascomparedtootheroxideglassesbuttheratioΩ4/Ω6ofthe~1.83indicatedthemtobefairlystable.WiththehelpofΩλparametersandluminescencedataforvariousemissionlines,radiativepropertiesfordifferentemissionlineswerecalculated.Thevaluesofradiativepropertiesindicatedthat4G5/2→6H7/2and4G5/2→6H9/2transitionsresponsiblefororangeluminescencemightbeusedinthedevelopmentofmaterialsforLED'sandotheropticaldevicesinthevisibleregion.
简介:单斜晶、六角形的LaPO4:5mol.%Eu3+黄磷与仅仅在一样的合成温度由一个热水的方法调整答案的pH价值被综合。被不同准备影响的Eu3+-dopedLaPO4,的微观结构,形态学和光致发光调节,被X光检查衍射(XRD)描绘,扫描电子显微镜学(SEM),Fourier变换红外线的光谱学(英尺红外),拉曼光谱学和光光谱学分别地。然而,标本在强壮的酸答案显示出单斜晶的结构它在弱酸答案和强壮的碱答案变成了六角形的结构。单斜晶的LaPO4:Eu3+显示出最长的长度到直径比率,它被归因于优先的生长[-112]。单斜晶的标本与六角形的标本相比在红外线的系列,拉曼乐队位置和费用转移(CT)展出了细微红移动。而且,谷物尺寸的计算结果,格子参数,在在拉曼模式和排放积分紧张的半最大值的完整的宽度在对分析结果的好同意。单斜晶的标本显示出最大的绝对的光量收益(0.4)和第二一生2(0.52ms),它与在CIE的红橘子的排放是一致的。5D07F1在六角形的标本占据了一个dominate位置,它显示在六角形的结构的更多的Eu3+被占据对称地点的倒置中心。