KMgF3:Ce3+,Tb3+纳米粒子中Ce3+→Tb3+的发光及能量传递

利用微乳液方法,合成了铈、铽共掺杂的氟镁钾纳米粒子,研究了体系中Ce3+→Tb3+的发光特性以及它们之间的相互作用,结果表明KMgF3:Ce3+Tb3+纳米粒子中存在Ce3+→Tb3+的能量传递过程,即Ce3+可以将吸收的能量直接传递给Tb3+离子,使得Tb3+的绿色发光强度大为增加.     

Photoluminescent Property Effect of Sc3+ on Er3+/y3+/yb3+ Doped Al2O3 Powders

The photoluminescence (PL) property effect of Sc3+ on the Er3+/Y3+/Yb3+ doped Al2O3 powders prepared by sol-gel method has been investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) implied that the distribution of dopants (Er3+ , Y3+ , Yb3+ , Sc3+) was improved effectively with the rise of Sc3+ concentration. The Fourier transform infrared spectra (FTIR) results demonstrated that the ligand around the quenching center -OH and the population of -OH were altered by introducing different amounts of Sc3+ . The PL intensity centered at 1530 nm was increasingly improved with the rise of Sc3+ concentration, as well as the corresponding full widths at the half maximum (FWHM) and lifetime. The optimized PL intensity was 4.7 times higher than that non-Sc3+ doped sample for the Al2O3 powders codoped with 10mol% Sc3+ . This material can be promising candidates for optical fiber amplifier.     

Die Perthioborate RbBS3, TIBS3 und TI3B3S10

The Perthioborates RbBS₃, TIBS₃, and Tl₃B₃S₁₀ . RbBS₃ (P2₁/c, a=7.082(2) Å, b=11.863(4) Å, c=5.794(2) Å, β=106.54(2)°) was prepared as colourless, plate-shaped crystals by reaction of stoichiometric amounts of rubidium sulfide, boron, and sulfur at 600°C and subsequent annealing. TlBS₃ (P2₁/c, a=6.874(3) Å, b=11.739(3) Å, c=5.775(2) Å, β=113.08(2)°) which is isotypic with RbBS₃ was synthesized from a sample of the composition Tl₂S · 2 B₂S₃. The glassy product which was obtained after 7 h at 850°C was annealed in a two zone furnace for 400 h at 400→350°C. Yellow crystals of TlBS₃ formed at the warmer side of the furnace. Tl₃B₃S₁₀ (P1 , a=6.828(2) Å, b=7.713(2) Å, c=13.769(5) Å, α=104.32(2)°, β=94.03(3)°, γ=94.69(2)°) was prepared as yellow plates from stoichiometric amounts of thallium sulfide, boron, and sulfur at 850°C and subsequent annealing. All compounds contain tetrahedrally coordinated boron. The crystal structures consist of polymeric anion chains. In the case of RbBS₃ and TlBS₃ nonplanar five-membered B₂S₃ rings are spirocyclically connected via the boron atoms. To obtain the anionic structure of Tl₃B₃S₁₀ every third B₂S₃ ring of the polymeric chains of MBS₃ is to be substituted by a six-membered B(S₂)₂B ring.     

BaLiF3:Ce 3+纳米粒子的制备及其光谱特性

BaLiF3属立方钙钛矿型复合氟化物, 作为高效闪烁晶体可用于热中子检测［1］. 由于其能带隙宽, 易于实现各种不同价态稀土离子掺杂, 可以获得许多可调谐性质, 因此它也是比较理想的光学功能材料的基质［2］. Ce3+激活的BaLiF3晶体作为紫外发射的短波固体激光材料和光放大材料的研究多有报道［3~5］     

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.     

钙钛矿型复合氧化物LaFeO3和LaCoO3的光催化活性

采用柠檬酸法合成了钙钛矿复合氧化物ＬａＦｅＯ３和ＬａＣｏＯ３,并以其为光催化剂对水溶性染料进行光催化降解实验,研究了不同光源和不同光照时间对降解脱色率的影响。结果表明ＬａＦｅＯ３和ＬａＣｏＯ３均有较强的光催化活性,而ＬａＣｏＯ３的光催化活性明显高于ＬａＦｅＯ３,这主要与Ｆｅ＾３＋和Ｃｏ＾３＋离子的电子构型以及Ｆｅ－Ｏ间和Ｃｏ－Ｏ间的结合能有关。     

Etude du Systeme LiPO3-Pr(PO3)3 Donnees sur LiPr(PO3)4

The LiPO₃-Pr(PO₃)₃ system was studied by micro-differential thermal analysis. The only new compound observed in the system was LiPr(PO₃)₄, melting incongruently at 1246 K. An eutectic appears at 926 K. Crystallographic data and powder diagram of the new compound are given. LiPr(PO₃)₄ crystallizes in the C2/c monoclinic system with unit cell: a=16.428(6), b=7.054(3), c=9.747(4) Å, β=126°31′(3), V=910.2 ų, Z=4. The IR and Raman spectra of this compound are given. This revised version was published online in July 2006 with corrections to the Cover Date.     

Michael condensation of 3-arylidene-3H-pyrrol-2-ones and 3-arylidene-3H-furan-2-ones with cyclohexanone

The Michael condensation in the series of 5-aryl-3-arylidene-3H-pyrrol-2-ones and 5-aryl-3-arylidene-3H-furan-2-ones, containing an activated C=C bond, with cyclohexanone was investigated. It was shown that the condensation products were 1,5-dicarbonyl compounds containing a heterocyclic fragment. The enolization of one of the oxo groups, leading to the formation of hydroxypyrrole or hydroxyfuran structures, was demonstrated by the spectral data. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 823–827, June, 2007.     

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.     

Fe_3O_4/SrTiO_3复合光催化剂降解甲基橙

用共沉淀法制备了SrTiO3光催化剂及Fe3O4/SrTiO3复合光催化剂.通过紫外-可见漫反射光谱、XRD、SEM-EDX对其进行表征,以甲基橙为探针分子考察其光催化性能.结果表明,适量Fe3O4的掺入可明显提高Sr-TiO3光催化剂对可见光的吸收,从而增强其光催化性能;在光降解甲基橙的反应中,掺杂10%Fe3O4的SrTiO3光催化剂其催化活性是纯SrTiO3光催化剂的两倍.     

Ce3+激活的LiSrBO3材料发光特性及晶体学格位研究

采用固相法制备了蓝白色LiSrBO3∶Ce3+材料. 测得LiSrBO3∶Ce3+材料的发射光谱为一个主峰位于436 nm的非对称单峰宽谱; 监测436 nm发射峰时所得材料的激发光谱为一个主峰位于369 nm的宽谱. 利用Van Uitert公式计算了Ce3+取代LiSrBO3中Sr时所占晶体学格位, 得出433 nm发射带归属于九配位的Ce3+发射, 469 nm发射带起源于八配位的Ce3+发射. 研究了Ce3+浓度对LiSrBO3∶Ce3+材料发光强度的影响, 研究结果显示, 随着Ce3+浓度的增大, 发光强度呈现先增大后减小的趋势, 在Ce3+摩尔分数为3%时到达峰值, 根据Dexter理论, 其浓度猝灭机理为电偶极-偶极相互作用. 引入Li+, Na+和K+作为电荷补偿剂时发现, LiSrBO3∶Ce3+材料的发射光谱强度均得到了明显的增强. 利用InGaN管芯(370 nm)激发LiSrBO3∶Ce3+材料时, 获得了很好的蓝白光发射, 色坐标为(x=0.289, y=0.293).     

3-Trifluoromethyl- and 3-difluoromethyl-thalidomides

Syntheses of racemic 3-trifluoromethyl- and 3-difluoromethyl-thalidomide starting from 2-(tert-butyloxycarbonylimino)-3,3,3-trifluoropropionate or -3,3-difluoropropionate as fluorine-containing building blocks are described.     

Growth and Characteristics of Nd^3＋：GdAl3（BO3）4 Crystal

Nd^3 :GdAl3(BO3)4(NGAB) crystal with the size of 30 mm was grown from the solvent system of K2O-Gd2O3-MoO3-B2O3 by combining accelerated seed rotation technology with medium seeded solution growth (MSSG) method,and its crystal structure has been determined by X-ray powder diffraction.It crystallizes in the trigonal system,space group R32 with a=9.2743(2),c=7.2438(1)A,V=538A^3,Z=3and Dc=4.379g/cm^3,The absorption and emission spectra of NGAB in the function of σ and π polarizations at room temperature have been measured.UV generation tuneable in 378-382nm,green(531nm) generation and blue generation tuneable in 436-443 nm as well as red(669)nm generation by self-frequency changing were obtained with the oupput of 105, 119.5,445and 19μJ/pulse,respectively,when the crystal was pumped by a dye laser.     

静电纺丝技术制备Y_2O_3∶Yb~(3+),Er~(3+)上转换纳米纤维及其表征

采用静电纺丝技术制备了PVA/[Y(NO3)3+Yb(NO3)3+Er(NO3)3]复合纳米纤维,将其在适当的温度下进行热处理,得到Y2O3∶Yb3+,Er3+上转换纳米纤维.XRD分析表明,复合纳米纤维为无定形,Y2O3∶Yb3+,Er3+上转换纳米纤维属于体心立方晶系,空间群为Ia3.SEM分析表明,复合纳米纤维的平均直径约为150nm;随着焙烧温度的升高,纤维直径逐渐减小.经过600℃焙烧后,获得了直径约60nm的Y2O3∶Yb3+,Er3+上转换纳米纤维.TG-DTA分析表明,当焙烧温度高于600℃时,复合纳米纤维中水分、有机物和硝酸盐分解挥发完毕,样品不再失重,总失重率为83%.FTIR分析表明,复合纳米纤维与纯PVA的红外光谱一致,当焙烧温度高于600℃时,生成了Y2O3∶Yb3+,Er3+上转换纳米纤维.该纤维在980nm的半导体激光器激发下发射出中心波长为521,562nm的绿色和656nm的红色上转换荧光,分别对应于Er3+离子的2H11/2/4S3/2→4Il5/2跃迁和4F9/2→4Il5/2跃迁.对Y2O3∶Yb3+,Er3+上转换纳米纤维的形成机理进行了讨论.     

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…     

The dealkylation of 2-diethylamino-3H-phenothiazin-3-one

2-Diethylamino-3H-phenothiazin-3-one was dealkylated to 2-ethylamino-3H-phenothiazin-3-one either by photolysis or pyrolysis.

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Entalkylierung von 2-Diethylamino-3H-phenothiazin-3-on (Kurze Mitteilung)

Zusammenfassung Die Titelverbindung wurde durch Photolyse oder Pyrolyse zu 2-Ethylamino-3H-phenothiazin-3-on entalkyliert.

     

Miscibility and crystallinity of poly(3-hydroxybutyrate)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) blends

With the objective of developing new biodegradable materials, the miscibility and the crystallinity of blends of poly(3-hydroxybutyrate), P(3HB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), have been studied. P(3HB) (300 kg mol⁻¹)/P(3HB-co-3HV)–10% 3HV (340 kg mol⁻¹) blends were prepared by casting in a wide range of proportions, and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The experimental values for the glass transition temperatures (T_g) are in good agreement with the values provided by the Fox equation, showing that the blends are miscible. It was observed that the T_g and the melting temperature (T_m) decreases with the increase in the P(3HB-co-3HV)–10% 3HV content, while the crystallization temperature (T_c) increases. FT-IR analyses confirmed the decrease on the crystallinity of P(3HB)/P(3HB-co-3HV)–10% 3HV blends with higher copolymer contents. Bands related to the crystallinity were changed, due to the copolymer content that produced miscible and less crystalline blends.     

Zur Kenntnis der ionischen Ozonide P(CH3)4O3 und As(CH3)4O3

On the Knowledge of the New Ionic Ozonides P(CH₃)₄O₃ and As(CH₃)₄O₃ P(CH₃)₄O₃ and As(CH₃)₄O₃ were prepared via ion exchange in liquid ammonia and characterized by X-ray-powder, IR, MS and DTA techniques. P(CH₃)₄O₃ and As(CH₃)₄O₃ are isotypic and have a wurtzite-like arrangement of ions with rotationally disordered O₃^?. (Powder data: P6₃mc; P(CH₃)₄O₃: a = 687.8(2), c = 964.6(3) pm; As(CH₃)₄O₃: a = 708.6(1), c = 991.0(3) pm). As(CH₃)₄O₃ shows a displacive phase transition at ?135°C. The low temperature phase is orthorhombic (a = 715.8(7), b = 1 209(1), c = 943.3(1) pm).     

Total synthesis of stevastelins B3 and C3: structure confirmation of stevastelin B3 and revision of stevastelin C3

The total synthesis of stevastelin B3, stevastelin C3 and 5-deoxy derivative of stevastelin C3, novel 13-membered cyclic depsipeptides, is described. This study unambiguously confirmed the proposed absolute structure of stevastelin B3, and revealed that the structure of stevastelin C3 is incorrect. The correct structure of stevastelin C3 was established by the total synthesis to be 5-deoxy derivative of the proposed structure.     

A study on the BF3 directed lithiation of 3-chloro- and 3-bromopyridine

The BF₃-directed lithiation of 3-chloro- and 3-bromopyridine (1a and 1b, respectively) has been investigated. The reactions of 3-chloro- or 3-bromopyridine–BF₃ adduct with LDA (1.3/1.1 equiv) followed by quenching with benzaldehyde or iodine exclusively gave the C-2 substituted products. However, when 2.2 equiv of LDA and dimethyl disulfide was used, a C-6 substituted product was obtained. Dilithiation of 1a and 1b has been studied with and without the involvement of BF₃ complexation. The role of Li?F(BF₃) interactions has been investigated by experimental and DFT calculations.