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101.
The samples of YBa3B9O18, LuBa3(BO3)3, α-YBa3(BO3)3 and LuBO3 powders have been synthesized by the solid-state reaction methods at high temperature and their X-ray excited luminescent properties were investigated. All the studied materials show a broad emission band in the wavelength range of 300-550 nm with the peak centers at about 385 nm for YBa3B9O18 and LuBa3(BO3)3, 415 nm for α-YBa3(BO3)3 and 360 nm for LuBO3 powders, respectively. Even though those compounds have the different atomic structures, they have the common structural feature of each yttrium or lutetium ion bonded to six separate BO3 groups, i.e., octahedral RE(BO3)6 (RE=Lu or Y) moiety. This octahedral RE(BO3)6(RE=Lu or Y) moiety seems to be an important structural element for efficient X-ray excited luminescence of those compounds, as are the edge-sharing octahedral TaO6 chains for tantalate emission. 相似文献
102.
稀土(Nd,Pr)(Ⅲ)双酞菁衍生物的合成,表征和气敏特性 总被引:3,自引:0,他引:3
合成了八-4-(四氢糖氧基)酞菁钕(Ⅲ)(A)、八-4-(β-萘氧基)酞菁钕(Ⅲ)(B)、八-4-(2,4-二叔戊基苯氧基)酞菁钕(Ⅲ)(C)和八-4-(2,4-二叔戊基苯氧基)酞菁镨(Ⅲ)(D)4种新的稀土(Nd、Pr)(Ⅲ)双酞菁衍生物,经元素分析、红外光谱、核磁共振谱表征。紫外可见光谱表明,它们在氯仿(10^-6mol/L)溶液中以单分子形式存在。热重分析证明配合物的热稳定性:B>C ̄D>A 相似文献
103.
Dominique Robert 《Journal of organometallic chemistry》2006,691(21):4393-4399
A series of yttrium and lutetium alkyl complexes [Ln(η5-C5Me4ZNR′-κN)(CH2SiMe3)(THF)n] (Ln = Y, Lu) was prepared by reacting the tris(trimethylsilylmethyl) precursor [Ln(CH2SiMe3)3(THF)2] with different linked amino-cyclopentadienes of the type (C5Me4H)ZNHR′ (Z = SiMe2, CH2SiMe2; R′ = tBu, Ph, C6H4-tBu-4, C6H4-nBu-4). The catalytic activity of these alkyl complexes in the hydrosilylation of 1-decene and styrene using PhSiH3 as reagent was examined under standard conditions. A significant influence of the ligand structure on the catalytic property (turnover frequency, regioselectivity) was observed with the yttrium complex [Y(η5-C5Me4CH2SiMe2NtBu-κN)(CH2SiMe3)(THF)] being the most active for 1-decene hydrosilylation. 相似文献
104.
Jens Niermann 《Journal of solid state chemistry》2004,177(7):2600-2609
The ternary aluminides R2Rh3Al9 (R=Y, La-Nd, Sm, Gd-Tm, Lu), R2Ir3Al9 (R=Y, La-Nd, Sm, Gd-Lu), and R2Pd3Al9 (R=Y, Gd-Tm) have been prepared by arc melting of the elemental components with an excess of aluminum and dissolving the aluminum-rich matrix in hydrochloric acid. They crystallize with Y2Co3Ga9-type structure: Cmcm, Z=4. The crystal structures of Ho2Rh3Al9 and Er2Ir3Al9 have been refined from single-crystal X-ray data; Ho2Rh3Al9: a=1316.8(3) pm, b=760.2(2) pm, c=933.7(2) pm, R=0.044 for 255 structure factors and 27 variables; Er2Ir3Al9: a=1313.8(2) pm, b=758.5(1) pm, c=933.8(2) pm, R=0.057 (392 F values, 27 variables). The structure may be viewed as consisting of atomic layers of the compositions A=R2Al3 and B=T3Al6 which alternate in the sequence ABAB along the z direction. Approximately 33% and 27% of the A layers were found to be misplaced in the crystals investigated for Ho2Rh3Al9 and Er2Ir3Al9, respectively. The magnetic properties of most iridium-containing compounds have been determined with a superconducting quantum interference device magnetometer. The yttrium and the lanthanum compounds show Pauli paramagnetism, others reflect the magnetic behavior of the rare-earth components. The magnetic ordering temperatures are all lower than 20 K. 相似文献
105.
A series of rare-earth iron borates having general formula LnFe3(BO3)4 (Ln=Y, La-Nd, Sm-Ho) were prepared and their magnetic properties have been investigated by the magnetic susceptibility, specific heat, and 57Fe Mössbauer spectrum measurements. These borates show antiferromagnetic transitions at low temperatures and their magnetic transition temperatures increase with decreasing Ln3+ ionic radius from 22 K for LaFe3(BO3)4 to 40 K for TbFe3(BO3)4. In addition, X-ray diffraction, specific heat, and differential thermal analysis (DTA) measurements indicate that the phase transition occurs for the LnFe3(BO3)4 compounds with Ln=Eu-Ho, Y, and its transition temperature increases remarkably with decreasing Ln3+ ionic radius from 88 K for Ln=Eu to 445 K for Ln=Y. 相似文献
106.
Jasmine N. Millican D.P. Young Julia Y. Chan 《Journal of solid state chemistry》2004,177(12):4695-4700
A new ternary compound, Ce2PdGa10, has been synthesized using Ga flux and characterized by single-crystal X-ray diffraction. Ce2PdGa10 adopts a tetragonal structure in the I4/mmm space group and is isostructural to Ce2NiGa10. Lattice parameters are , , , and Z=2. The compound is metallic (dρ/dT>0), with the resistance decreasing roughly linearly with temperature from 300 to 175 K. The magnetic susceptibility of Ce2PdGa10 is consistent with local-moment paramagnetism and no long-range magnetic ordering occurs down to 2 K. A large positive magnetoresistance over 200% is observed at 2 K for fields of 9 T. In this paper, we present the structure and physical properties of Ce2PdGa10 and compared them to CePdGa6. 相似文献
107.
Ring-opening polymerization of ε-caprolactone (CL) catalyzed bylanthanocenes, O(C_2H_4C_5H_3CH_3)_2YCl (Cat-YCl) and Me_2Si[(CH_3)_3SiC_5H_3]_2NdCl(Cat-NdCl) has been carried out for the first time. It has been found that both yttroceneand neodymocene are very efficient to catalyze the polymerization of CL, giving high molec-ular weight poly (ε-caprolactone) (PCL ). The effects of [cat] / [ε- CL] molar ratio, polymeriza-tion temperature and time, as well as solvents were investigated and polymerization tem-perature is found to be the most important factor affecting the polymerization. The bulkpolymerization gives higher molecular weight PCL and higher conversion than that in solu-tion polymerization. NaBPh_4 was found to promote the polymerization of ε-caprolactone,and thus to increase both the polymerization conversion and MW of poly (ε- caprolactone ). 相似文献
108.
Danuta M. Czakis-Sulikowska Joanna Radwańska-Doczekalska Grzegorz Sójka 《Monatshefte für Chemie / Chemical Monthly》1984,115(8-9):961-973
4,4-Dipyridyl complexes of rare-earth thiocyanates of the formulaLn(4-dipy)2(NCS)3·5H2O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 4-dipy = 4,4-dipyridyl) have been synthesized. The IR spectra of these compounds and other physical properties are discussed. The thermal decomposition of some compounds (in the order Gd ÷ Lu) has been investigated.
4,4-Dipyridylkomplexe von Seltenerdmetallthiocyanaten
Zusammenfassung Es wurden 4,4-Dipyridylkomplexe des TypesLn(4-dipy)2(NCS)3·5H2O mitLn = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu und Y dargestellt. Die IR-Spektren und andere physikalische Eigenschaften werden diskutiert und die thermische Zersetzung von einigen Verbindungen (in der Reihe Gd ÷ Lu) untersucht.相似文献
109.
B. M. Epelbaum K. Shimamura K. Inaba S. Uda V. V. Kochurikhin H. Machida Y. Terada T. Fukuda 《Crystal Research and Technology》1999,34(3):301-309
In spite of their superior laser and polarizer properties rare-earth orthovanadates (REVO4) single crystals have not been adopted yet into extensive industrial applications because of crystal growth difficulties. The main problems of CZ technique are compositional change and diameter instability. This work presents the first attempt to apply the edge-defined film-fed growth (EFG) technique by which well-shaped REVO4crystals have been grown directly. The capillary properties of YVO4 and GdVO4 melt have been measured. The applicability of shaped growth for rare-earth orthovanadate family was approved by successful EFG growth of transparent rod-like macro-defect-free single crystals of YVO4 and GdVO4. We address two main approaches to enhance the quality of EFG crystals: (i) meniscus and crystal shape stability dependence on die top shape and (ii) the strategy of effective operating control. Concave die top was found to be the best choice for high-quality EFG growth of REVO4 along [001] direction. The spectral analysis of weight signal from growing crystal was shown to be a useful feedforward clue to prevent crystallinity degradation at a very early stage. A reasonable stability of the EFG process was achieved using [211], [101], [001] and [100] pulling directions. 相似文献
110.
At 1050 ?C boron combines with sodium forming a boride of formerly unknown composition and crystal structure. The investigation of the homogeneous, monophasic, and crystalline powder was performed using X‐ray (23 ?C) and neutron (–271.5 ?C) diffraction methods. The structure solution led to an unusual arrangement of boron atoms, characterized by two different types of polyhedra, a distorted pentagonal bipyramid and a distorted octahedron. The Rietveld refinement of the crystal structure was carried out in the orthorhombic space group Cmmm (X‐ray: a = 18.6945(6) Å, b = 5.7009(2) Å, c = 4.1506(1) Å, V = 442.35(1) Å3, Z = 2; Rwp = 0.087, Rp = 0.067). 相似文献