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81.
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
82.
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
83.
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
84.
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
85.
Investigations about the Stability Range of the CaAl2Si2 Type Structure in the Case of Ternary Silicides Five compounds LnAl2Si2 (Ln: trivalent rare-earth metal, Y) were synthesized by heating the elements at 800°–1000 °C. They are isotypic and crystallize in the CaAl2Si2 type structure (P 3 m1; Z = 1) (lattice constants see “Inhaltsübersicht”). The electronic structures (LMTO band structure calculations) of CaAl2Si2 and YAl2Si2, the latter one is in accordance to Ln3+(Al3+)2(Si4–)2 not electrovalent, are discussed with regard to the bondings and the electrical conductivity respectively. Investigations of GdAl2–xMnxSi2 mixed crystals showed, that the structure type already at low Mn content (x ≈ 0,3) changes from CaAl2Si2 (GdAl2Si2) to ThCr2Si2 type structure (GdMn2Si2). 相似文献
86.
人体血浆中15种超良量稀土元素的电感耦合等离子体质谱法 … 总被引:1,自引:1,他引:0
本文用电感耦合等离子体质谱法测定了人体血浆中的稀土元素。在优化的条件下 ,以内标法测得的各种纯水溶液的检测限在 0 .7(Eu)~ 5 .4(Gd) ng·L- 1范围内。研究了 K,Na,Ca,Fe等基体元素对稀土测定的影响。以 In为内标元素补偿样品基体效应以及灵敏度飘移。比较了直接稀释、HNO3- H2 O2 消解及 HNO3-HCl O4消解 3种样品处理方法 ,用 1% HNO3直接稀释样品可满足轻稀土元素的定量分析要求 ,方法的定量测定下限≤ 1μg·L- 1。 相似文献
87.
S.-Y. Zhao S.-B. Lei S.-H. Chen H.-Y. Ma S.-Y. Wang 《Colloid and polymer science》2000,278(7):682-686
In this article the effect of field strength, temperature and square-wave pulse on the deposition structure of gold nanoparticles
is investigated and 2D structures of silver and two kinds of rare-earth carbonate particles are synthesized by electrophoretic
deposition (EPD). The results indicate that EPD is a general phenomenon that occurs on the electrode/sol interface and that
the EPD method may be developed for the assembling of 2D structures of nanoparticles. On the other hand, the results also
show that the composition and surface condition as well as the size distribution of the particles can affect the order of
the particles in the monolayer.
Received: 7 October 1999/Accepted: 25 January 2000 相似文献
88.
89.
LaMnO3稀土纳米材料及催化性能 总被引:8,自引:0,他引:8
As catalytic materials, nanometer rare earth perovskites LaMnO3 were p repared by NaOH Na2CO3 coprecipitation, followed by supercritical drying, vacuu m drying and air drying respectively. The effect of drying processes was studied on the catalyst performance through XRD, TEM, SEM and BET analysis. The results demonstrated that about 30 nm LaMnO3 particles could be prepared by three dryin g processes respectively. The catalyst materials LaMnO3 dried in vacuum presente d the largest specific surface area as 28.71 m2•g-1. Compared to the catalyst prepared by dipping cordierite directly in the salt solutions, nanometer LaMnO3 showed better catalytic activity. The light off temperatures for CO and HC oxid ation were both lowered by 100 ℃, and its NOx conversion could be up to 100 % at 570 ℃. 相似文献
90.
Gafurov MR Ivanshin VA Kurkin IN Rodionova MP Keller H Gutmann M Staub U 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,161(2):210-214
We investigate the low temperature X-band electron paramagnetic resonance (EPR) of YBa(2)Cu(3)O(x) compounds with x congruent with 6.0 doped with Dy(3+), Tb(3+), and Nd(3). The EPR spectra of Dy(3+) and Tb(3+) have been identified. The EPR of Tb(3+) is used also to study the effect of suppression of high T(c) superconductivity by doping with Tb(3+). The EPR of Nd(3+) is probably masked by the intense resonance of Cu(2+). All experimental EPR results compare well with theoretical estimations. 相似文献