Ce^(3+)⁃Cr^(3+)共掺杂Ba_(3)Sc_(4)O_(9)荧光材料的发光性能

红光‐近红外光谱技术在医疗领域具有广泛的应用。但对于当下采用蓝光LED激发荧光材料实现红光‐近红外光谱输出的器件结构而言,则普遍存在蓝光过剩的问题。本文提出了通过构筑Ce^(3+)→Cr^(3+)能量传递从而实现抑制器件蓝光输出的策略。以Ba_(3)Sc_(4)O_(9)为研究对象,采用Ce^(3+)/Cr^(3+)共掺杂,研究了其发光性能。结果表明,共掺杂的Ba3Sc4O9∶Ce^(3+)/Cr^(3+)同时具备了红光和近红外光发射能力,发射主峰分别位于585 nm和835 nm;Ce^(3+)→Cr^(3+)能量传递效率达50.92%。所封装的近红外LED器件的蓝光强度下降了78%,而Cr^(3+)的发射强度增至181%。

Cr_2O_7^(2-)/Cr^(3+)和Ce^(4+)/Ce^(3+)电解液作媒质间接合成对甲氧基苯甲醛

在高剪切混合乳化机搅拌下,通过对Cr2O72- /Cr3+和 Ce4+/Ce3+两种媒质间接合成对甲氧基苯甲醛槽外反应的研究,得到合成对甲氧基苯甲醛的优选条件分别为:原料配比n(Cr2O72-):n(p-CH3O-C6H4-CH3)=1:6,反应温度 80℃,反应时间10min,对甲氧基苯甲醛反应收率90.5%;原料配比 n(Ce4+):n(p-CH3O-C6H4-CH3)=1:1,反应温度30℃,反应时间6min,对甲氧基苯甲醛反应收率97.1%。结果表明,Ce4+/Ce3+做媒质产品时-空效率较低,这是Ce4+/Ce3+媒质存在的本质缺陷;而Cr2O72-/Cr3+做媒质产品时-空效率提高近2倍,显著地增加产品的产量,提高了经济效益。

Luminescent properties of Ce^(3+)/Tb^(3+) co-doped glass ceramics containing YPO_4 nanocrystals for W-LEDs

Ce^3＋/Tb^3＋ co-doped transparent glass ceramics containing YPO4 nanocrystals were prepared using high temperature melting method,and their structural and luminous properties were investigated.XRD analysis and TEM images confirmed the existence of YPO4 nanocrystals in glass ceramics.The transmission spectra proved that the glass ceramics specimens still maintained a high transparency.Then the excitation and emission spectra of the Ce^3＋ and Tb^3＋ single-doped and co-doped glass and glass ceramics were discussed,which proved that the glass ceramics had better luminescent properties.Under the near ultraviolet（331 nm）excitation,the broadband emission located at 385 nm was observed which was ascribed to 5d→~2F（5/2） and ~2F（7/2） transition of Ce^3＋ ions.Several characteristic sharp peaks centered at 489,543,578 and 620 nm originated from the ~5D4 to ~7FJ（J=6,5,4,3）of Tb^3＋ ions.The decay time of Tb^3＋ ions at 543 nm and the relevant energy levels of Ce^3＋ ions and Tb^3＋ ions illustrated the transfer process from Ce^3＋ ions to Tb^3＋ ions.The best CIE chromaticity coordinate of the glass ceramics specimen was calculated as（x=0.3201,y=0.3749）,which was close to the NTSC standard values for white（x=0.333,y=0.333）.All the results suggested that the YPO^4-based Ce^3＋/Tb^3＋ co-doped glass ceramics could act as potential luminescent materials for white light-emitting diodes.

Ce^(3+)离子敏化Eu^(3+)∶Cr^(3+)∶Sm^(3+)∶YAG外延层的荧光现象

对Ce3+ ∶Eu3+ ∶Cr3+ ∶Sm3+ ∶YAG处延层中的荧光敏化现象进行了报道和分析 ,在较高浓度的Ce3+ 离子掺杂时 ,外延层在蓝色、绿色波段出现了新的荧光谱线 ,可解释为在Ce3+ 离子敏化作用下 ,Eu3+ 离子产生了由高位激发态能级5Di(i=1,2 ,3)直接到基态能级7Fj(j =0 ,1,2 ,3)的辐射跃迁过程 ,并且这种Ce3+ ∶Eu3+ ∶Cr3+ ∶Sm3+ ∶YAG外延层还是一种新颖的白色单晶荧光材料。