白光LED用荧光材料Ba3Gd（BO3）3∶Eu^（3＋）的发光性能研究

用高温固相反应法制备了稀土离子Eu^3＋掺杂的三元稀土硼酸盐Ba3Gd（BO3）3发光材料,通过X射线衍射（XRD）、荧光光谱和扫描电镜（SEM）等测试手段对Ba3Gd（BO3）3∶Eu^3＋荧光粉的制备条件、发光性能以及形貌进行了研究。XRD结果表明,在1000℃时可得到Ba3Gd（BO3）3纯相。扫描电镜照片显示颗粒基本为球形,粒径约为200-400 nm。发光光谱测试表明,Ba3Gd（BO3）3∶Eu^3＋荧光粉在近紫外区（UV）（396 nm）和蓝光区（466 nm）可以被有效地激发,分别用255和396 nm的紫外光激发样品时,以Eu3＋的5D0-7F2（611和616 nm）超灵敏跃迁为主要发射峰。当Eu3＋的掺杂浓度为10%（摩尔分数）时,Ba3Gd（BO3）3∶Eu3＋在611和616 nm处的发光强度最大。因此,这种荧光粉是一种可能应用在白光LED上的红色荧光材料。     

Growth and Spectral Properties of Yb^3＋-doped Ba3Gd（BO3）3 Crystal

Crystal of Yb3+-doped Ba3Gd(BO3)3 has been grown by the Czochralski method. The spectroscopic characterizations have been investigated at room temperature. The Yb3+:Ba3Gd(BO3)3 crystal exhibits broad absorption at 976nm with FWHM of 7nm and large overall spitting of 2F7/2 manifold (823cm-1). The absorption and emission cross sections are 5.09×10-21cm2 at 976nm and 0.97×10-21cm2 at 1040nm,respectively. The fluorescence lifetime is 2.84 ms.     

La(NO3)3和Pr(NO3)3对高岭石脱羟基动力学的影响

采用热重和微商热重(TG/DTA)综合热分析技术在不同升温速率下研究了掺入La(NO₃)₃和Pr(NO₃)₃的高岭石的热分解过程, 利用Coats-Redfern积分法和Achar微分法对热分析实验数据进行动力学计算, 得到了高岭石脱羟基反应过程中的控制机理函数、 活化能和指前因子等动力学参数; 分析了2种稀土掺入对高岭石脱羟基过程动力学参数的影响, 并用Ozawa法对活化能进行了验证. 结果表明, 未掺稀土和掺入Pr(NO₃)₃的高岭石的脱羟基反应过程均受化学反应模型F₃控制, 反应的活化能分别为307.94和282.86 kJ/mol, 指前因子lnA的值分别为47.8980和44.1718; 掺入La(NO₃)₃的高岭石脱羟基反应过程控制机理函数发生改变, 受化学反应模型F₂控制, 反应活化能为196.02 kJ/mol, 指前因子lnA的值为29.5551. 与未掺稀土的高岭石对比, 掺入Pr(NO₃)₃后活化能和指前因子略有降低; 而掺入La(NO₃)₃后则显著降低, 分别降低了36.34%和38.30%. 采用Ozawa法验证得到的活化能与Coats-Redfern积分法和Achar微分法结果一致.     

Ba_3Y(PO_4)_3∶Dy~(3+),Eu~(3+)单基质白光荧光粉的制备与发光性能

为了探究在Dy~(3+)掺杂Ba_3Y(PO_4)_3荧光粉中共掺Eu~(3+)离子对其发光性能的影响,我们采用传统高温固相法制备了一系列Dy~(3+)、Eu~(3+)单掺杂和共掺杂Ba_3Y(PO_4)_3荧光粉。通过X射线衍射(XRD)、荧光发射光谱和荧光衰减曲线对样品进行了表征。结果表明,所制备的荧光粉呈闪铋矿立方相。在近紫外光激发下,Ba_3Y(PO_4)_3∶Dy~(3+)发射光谱在487和578 nm处有两个窄带发射峰,呈冷白光发射;Ba_3Y(PO_4)_3∶Eu~(3+)发射光谱的窄带发射位于594和616 nm处,呈发橙红光。在Ba_3Y(PO_4)_3∶Dy~(3+),Eu~(3+)中,由于Eu~(3+)离子补偿Dy~(3+)冷白光发射所缺的红色组分,从而实现了色纯度高、色温适中的暖白光发射。进一步探索了Ba_3Y(PO_4)_3∶Dy~(3+),Eu~(3+)荧光粉发光机理。所制备的Ba_3Y(PO_4)_3∶Dy~(3+),Eu~(3+)单基质白光荧光粉在白光近紫外激发白光二极管(UVWLED)领域具有潜在应用价值。     

NaTaO_3及NaTaO_3∶Bi~(3+)光催化剂的光致发光光谱研究

采用光致发光光谱技术对一系列不同条件下制备的NaTaO3及不同掺杂量的NaTaO3∶Bi3 进行了研究.结果表明,NaTaO3的发光性质与其制备条件密切相关在钠离子不足的条件下合成的样品,其发光带主要位于515和745nm左右;而在钠离子充足条件下合成的样品,其发光带位于460nm左右,随着n(Na)/n(Ta)的降低,发光带向长波长方向移动;掺入Bi3 之后,其发光峰由515nm移至455nm,随着Bi3 掺入量的增加,455nm的发光带强度减弱.515nm的发光带与替位缺陷Ta.N.a..相关;745nm的发光带与VN`a缺陷相关;而460nm的发光带与本征TaO6基团相关.将Bi3 掺入到钽酸钠样品,TaN..a..由BiN..a替代,相应的发光带向高的n(Na)/n(Ta)方向移动,从而呈现出本征TaO6基团的发光带.     

Dy^3＋在Ba3La（B03）3中的光致发光

研究了Ba3La(BO3)3基质中Dy^3 的光致发光特性；探讨了RE^3 的电荷半径比(z／r)和Ce^3 ，Dy^3 含量对Dy^3 发光强度及发光颜色的影响；分析了Ba3La(BO3)3中Ce^3 对Dy^3 发光的敏化作用；确定了Dy^3 的^4F9／2→^6H15／2及^4F9／2→^6H13/2跃迁发射的浓度猝灭机制均为电偶极-电四极相互作用。     

GdF3∶Er^3＋,Yb^3＋的合成和上转换发光特性

采用水热法制备了Er^3＋离子浓度为3%,Yb^3＋离子浓度分别为10%,20%的GdF3∶Er^3＋,Yb^3＋。XRD结果表明：合成的样品均为正交结构的GdF3,Gd0.87Yb0.10Er0.03F3和Gd0.77Yb0.20Er0.03F3样品的晶粒尺寸分别为28和26nm。研究了980nm红外光激发的上转换发射光谱。结果表明：红光和绿光发射分别来自于Er^3＋离子的2H11/2,4S3/2→4I15/2和4F9/2→4I15/2跃迁。样品的绿光发射强度较红光发射强。但绿光和红光发射的相对强度比例与Yb^3＋离子浓度有关。对Gd0.87Yb0.10Er0.03F3和Gd0.77Yb0.20Er0.03F3样品中可能的上转换发光机制进行了讨论。     

Ca_4GdO(BO_3)_3:Eu~(3 ),Sm~(3 )的发光及离子间的能量转移

Ca4 RO( BO3 ) 3 ( R=La,Ln,Y)三硼酸盐具有优良的非线性特征 . Khamaganova等[1] 以Pb O作助熔剂在合成 Ca4 Sm2 ( BO3 ) 4的过程中发现了一种新相 ,经过结构分析判定是一种新的化合物 .Norrestam等通过高温固相反应合成出此类三硼酸盐 .Iiykhuin[2 ] 对 Ca4 RO( BO3 ) 3( R=Lu,Tb,Gd)的结构进行了研究 .Dirkse等 [3 ]报道了 Ca4 Gd O( BO3 ) 3 粉末的发光特性 .1 996年 ,Aka[4 ] 采用提拉法 ( Czochralski)首次生长出较大尺寸的 Ca4 Gd O( BO3 ) 3 单晶 .孟宪林等 [5]报道了 Ca4 YO( BO3 ) 3 :Nd晶体的激光发射和自倍…     

LaBO_3、GdBO_3中Eu~(3+)和Bi~(3+)的发光特性及其相互作用

在紫外光(UV)和阴极射线(CR)激发下,系统地研究了LaBO_2、GdBO,中Eu~(3+)和Bi~(3+)的发射光谱、激发光谱及发光寿命与组成和结构的关系。结果表明,在文石结构的LaBO_3中Eu~(3+)的发射光谱与在YBO,结构的GdBO_3中Eu~(3+)的光谱有明显的差別。在紫外光激发下,GdBO_3中的Bi~(3+)能敏化Eu~(3+)的发光,而在LaBO_3中的Bi~(3+)却猝灭Eu~(3+)的发光。     

Y2O3包覆LiCo1/3Ni1/3Mn1/3O2的电化学性能

通过在硝酸钇水溶液浸渍并焙烧的简单工艺, 在LiCo1/3Ni1/3Mn1/3O2材料表面包覆了一层Y2O3. 采用X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM), 循环伏安(CV)和恒流充放电对包覆和未包覆的LiCo1/3Ni1/3Mn1/3O2进行了测试分析. 结果表明, Y2O3包覆并没有改变LiCo1/3Ni1/3Mn1/3O2的晶体结构, 只存在于LiCo1/3Ni1/3Mn1/3O2的表面; 与未包覆的材料相比, Y2O3包覆后的材料在高电位下具有更好的容量保持率和放电容量. CV测试表明, 包覆层的存在有效抑制了材料层状结构的转变及电极与电解液的负反应.     

Die Kristallstruktur des W3CoB3 und der dazu isotypen Phasen Mo3CoB3, Mo3NiB3 und W3NiB3

Zusammenfassung Mo₃CoB₃, Mo₃NiB₃, W₃CoB₃ und W₃NiB₃ kristallisieren in einem eigenen Typ (W₃CoB₃-Struktur). Das trigonal prismatische Bauelement [T ₆B]^* ist zu Ketten vereinigt, wobei B₃-Gruppen entstehen. Die Phasen sind vermutlich Bor-reicher als obiger Formel entspricht.

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The crystal structure of W₃CoB₃ and the isotypic phases Mo₃CoB₃, Mo₃NiB₃, and W₃NiB₃

Mo₃CoB₃, Mo₃NiB₃, W₃CoB₃, and W₃NiB₃ were found to possess a new type of crystal structure (W₃CoB₃-structure type). Trigonal prismatic groups [T ₆B]^* are linked together forming chains in such a way that B₃-groups occur. These borides do probably exist with a larger amount of boron as to compared with the formula.

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γ-Nitro-γ-butyrolacton

γ-Nitro-γ-butyrolactone By oxidation of 3-(1-nitro-2-oxocyclohexyl)propanal ( 1 ) with KMnO₄, besides 3-(1′-nitro-2′-oxocyclohexyl)pripionic acid ( 2 ), the complete hydrolysis product 4-oxononanedioic acid ( 4 ) and the oxidized semi-hydrolysis product 5-(2-nitro-5-oxotetrahydro-2-furyl)pentanoic acid ( 3 ) were formed. The crystalline 3 decomposes at r.t. forming 4 and nitrous gases; its structure was established by X-ray determination.     

Synthesis of γγγ-trifluorocarbonyl compounds

γγγ-Trifluorocarbonyl compounds are easily obtained in a good yield by introduction of the 1,1,1-trifluoroethyl moiety (CF₃-CH₂-) on the -methylene group of a ketone.     

K3SbSe3, Rb3SbSe3 und Cs3SbSe3 – Synthese und Kristallstruktur

K₃SbSe₃, Rb₃SbSe₃, and Cs₃SbSe₃ – Synthesis and Crystal Structure The compounds K₃SbSe₃, Rb₃SbSe₃ and Cs₃SbSe₃ were synthesized by heating mixtures of Sb₂O₃ and an alkalicarbonate in a stream of hydrogen saturated by selenium in a temperature range between 750 °C and 800 °C. The compounds crystallize isostructural with Na₃AsS₃. A comparison of atomic distances and bond angles with those of the isostructural arsenic and bismuth compounds shows the effect of lone pairs.     

Freezing the polarization of CH3NH3PbI3 and CH3NH3PbI3-xClx perovskite films

Thin films of methylammonium lead halides, CH₃NH₃PbI₃ and CH₃NH₃PbI_3-xCl_x, were deposited onto symmetrical microstructured electrode arrays of gold or platinum on Si/SiO₂ wafers. Polarization studies were carried out on perovskite films under vacuum in the dark. For poling, a constant voltage was applied to the samples while the temperature was cycled between 295 K and 4 K. The measured current densities depending on the temperature showed distinct characteristics relating strongly to the crystal phase and the dielectric properties of the perovskite films. Voltage sweeps were carried out at different scan rates at specific temperature intervals after poling. The polarization of the films due to the migration of iodide vacancies in direction of the blocking perovskite/metal interface was frozen almost up to room temperature. Charge carriers were only able to cross the blocking barrier and contribute to the current where the ions have accumulated during poling. All J-V curves showed hysteresis: inverted and regular hysteresis at room temperature and below, respectively. Inverted hysteresis originates from the slow accumulation of ions at the blocking barrier, while regular hysteresis arises from a distortion in the adjacent crystals which will be discussed.     

Synthesis of some derivatives of 3-amino-3-desoxyerythrose and 3-amino-3-desoxy-D-3-erythrose

The synthesis of derivatives of 3-amino-3-deoxy-L-erythrose by LAH or LAD reduction of the oxime of 1,2-O-isopropylidene α-L -glycero-tetros-3-ulofuranose is described.     

K3BiSe3, Rb3BiSe3 und Cs3BiSe3 – Substitutionsvarianten des Th3P4-Typs

K₃BiSe₃, Rb₃BiSe₃, and Cs₃BiSe₃ – Derivatives of the Th₃P₄ Structure Type The compounds K₃BiSe₃, Rb₃BiSe₃, and Cs₃BiSe₃ were synthesized by heating mixtures of Bi₂O₃ and the respective alkalicarbonate in a stream of hydrogen saturated by selenium at 850°C. Thin crystals of the compounds appear red in transmitted light. They crystallize isostructural with Na₃AsS₃, space group P2₁3, lattice constants a = 9.771(5) Å, a = 10.161(3) Å, and a = 10.587(5) Å for K₃BiSe₃, Rb₃BiSe₃, and Cs₃BiSe₃, respectively. The Na₃AsS₃ structure type is a derivative of the Th₃P₄ structure type.     

Die Akzeptoreigenschaften von AsCl3, AsBr3, asJ3, SbCl3, SbBr3 und SbJ3

Zusammenfassung Es wurden die Enthalpien der Reaktionen von AsCl₃, AsBr₃, AsJ₃, SbCl₃, SbBr₃ und SbJ₃ mit Tributylphosphat, N,N-Dimethylacetamid und Hexamethylphosphorsäuretriamid bestimmt. Das Verhalten der Addukte bei Gegenwart eines Überschusses der Donoren wird beschrieben.

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Acceptor properties of AsCl₃, AsBr₃, AsI₃, SbCl₃, SbBr₃, and SbI₃

The enthalpies of the reactions of AsCl₃, AsBr₃, AsI₃, SbCl₃, SbBr₃ and SbI₃ with tributylphosphate, N,N-dimethylacetamide and hexamethylphosphoric acid triamide were measured. The behavior of the adducts in the presence of excess donor molecules is described.

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3x-pyrrolizin-3-ones

Condensation of pyrrole-2-dithiocarboxylates with CH acids containing ester groups, in the KOH-DMSO system, was used to prepare previously unknown 1-alkylthio-3H pyrrolizin-3-ones. The latter, treated with secondary amines, are readily converted to the corresponding 1-amino derivatives.     

3-H-pyrrolizin-3-ones

Previously unknown 1-alkylthio-3H-pyrrolizin-3-ones have been obtained by the condensation of pyrrole-2-dithiocarboxylates with CH acids containing ester groupings in the KOH-DMSO system. On treating the products with secondary amines they are readily converted into the corresponding 1-amino derivatives.Irkutsk Branch of the Russian Academy of Sciences, Irkutsk 664033. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 919–924, July, 1996. Original article submitted May 2, 1996.