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1.
The growth and electronic structure of vapor-deposited Sm on a well-ordered Al(2)O(3)/Ni(3)Al(111) ultrathin film under ultrahigh vacuum conditions at room temperature have been studied comprehensively using synchrotron radiation photoemission spectroscopy, X-ray photoelectron spectroscopy, work function measurements, scanning tunneling microscopy, and low-energy electron diffraction. Our results indicate that at room temperature Sm grows in a layer-by-layer fashion up to at least 1 ML, followed by three-dimensional growth. The interaction of Sm with Al(2)O(3) thin films leads to an initial oxidation of Sm, accompanied by a parallel reduction of the Al(2)O(3) substrate. Both the oxidation states of Sm(2+) and Sm(3+) are found at low coverage (<1 ML). The concentration of Sm(2+) saturates below 0.4 ML, while that of Sm(3+) keeps increasing until the metallic state of Sm appears at high coverages. 相似文献
2.
应用AES,LEED,XPS和TDS研究了Rh(100)上Sm膜和Sm/Rh表面合金以及CO在这两类模型表面的吸附与反应.室温下Sm在Rh(100)上的生长遵从SK模式,Sm膜经900K高温退火后可形成有序表面合金.在室温制备的Sm膜/Rh(100)表面上,室温下CO在Sm上的吸附改变了表面结构,生成SmOx和表面碳.随着Sm覆盖度的增加,低温脱附峰(α-CO)面积迅速下降,且峰温向高温方向位移;表明Sm的空间位阻和电子效应同时起作用.在Sm/Rh合金表面上,CO在约590K出现新的脱附峰,可归属为受Sm电正性修饰的Rh原子上的CO脱附峰 相似文献
3.
Li HX Ren ZG Zhang Y Zhang WH Lang JP Shen Q 《Journal of the American Chemical Society》2005,127(4):1122-1123
The complex [{(TMS)2N}4(mu4-Cl)Sm4(mu-SPh)4(mu3-Cl)Li(THF)] has been formed by protonolysis of [(Me3Si)2N]3Sm(mu-Cl)Li(THF)3 with 1 equiv of HSPh, which contains a square array of Sm(III) ions connected by a central mu4-Cl ligand. The edges of the square Sm4 array are bridged by four mu3-Cl and four mu-SPh ligands. The four Sm atoms and Li atom are connected by four mu3-Cl ligands. 相似文献
4.
M. Korenko Y. V. Stulov S. A. Kuznetsov M. Ambrová B. Kubíková 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):589-595
This article is focused on the electrochemical investigation (cyclic voltammetry and related studies) of the redox couple Sm(III)/Sm(II) in an eutectic LiF–CaF2 melt containing SmF3. The first step of reduction for Sm(III) ions involving one electron exchange in soluble/soluble Sm(III)/Sm(II) system was found on a tungsten electrode. The study of the Sm(II)/Sm(0) electrode reaction was not feasible, due to insufficient electrochemical stability of LiF–CaF2. The first step was found reversible at temperatures 1,075 and 1,125 K up to polarization rate 1 V/s and at temperature 1,175 K the process was reversible at all sweep rates applied in this study. The diffusion coefficients (D) of Sm(II) and Sm(III) ions were determined by cyclic voltammetry, showing that D decreases when oxidation state increase, while the activation energy of diffusion (E a) increases. The standard rate constants of charge transfer (k s) were calculated for the redox couple Sm(III)/Sm(II) at 1,075 and 1,125 K based on the data of cyclic voltammetry. 相似文献
5.
Through the combination of Sm(III) spin carriers with a Fe(III) system, the largest Fe-Ln cluster so far has been synthesized. To our knowledge, the new complex, Fe(12)Sm(4), is the first Sm(III) single-molecule magnet. Furthermore, Fe(12)La(4) and Fe(12)Gd(4) have also been synthesized to help understand the magnetic exchange interactions and origin of magnetic anisotropy in Fe(12)Sm(4). 相似文献
6.
To compare the ligand-based reduction chemistry of (EPh)(-) ligands in a metallocene environment to the sterically induced reduction chemistry of the (C(5)Me(5))(-) ligands in (C(5)Me(5))(3)Sm, (C(5)Me(5))(2)Sm(EPh) (E = S, Se, Te) complexes were synthesized and treated with substrates reduced by (C(5)Me(5))(3)Sm: cyclooctatetraene; azobenzene; phenazine. Reactions of PhEEPh with (C(5)Me(5))(2)Sm(THF)(2) and (C(5)Me(5))(2)Sm produced THF-solvated monometallic complexes, (C(5)Me(5))(2)Sm(EPh)(THF), and their unsolvated dimeric analogues, [(C(5)Me(5))(2)Sm(mu-EPh)](2), respectively. Both sets of the paramagnetic benzene chalcogenolate complexes were definitively identified by X-crystallography and form homologous series. Only the (TePh)(-) complexes show reduction reactivity and only upon heating to 65 degrees C. 相似文献
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ADSORPTION OF SAMARIUM(Ⅲ) ON DIGLYCOLAMIDIC ACID RESIN 总被引:3,自引:0,他引:3
The sorption behavior and mechanism of a novel chelate resin, diglycolamidic acid resin(DAAR), for Sm(Ⅲ) were investigated. The optimal sorption condition of DAAR for Sm(Ⅲ) is pH=6.0 in HAc-NaAc medium. The statically saturated sorption capacity is 190mg/g resin at 298K.The Sm(Ⅲ) adsorbed on DAAR can be ehuted reaching 100% by 0.5~2.0mol/L HCl used as eluant.The resin can be regenerated and reused without apparent decrease of sorption capacity. The apparent sorption rate constant is k29s= 1.96 × 10-5 s-1. The apparent activation energy is 26k J/mol.The sorption behavior of DAAR for Sm(Ⅲ) obeys the Freundlich isotherm. The thermodynamic sorption parameters, enthalpy change △H of DAAR for Sm(Ⅲ) is 16. 9kJ/mol. The molar coordination ratio of the functional group of DAAR to Sm (Ⅲ) is 3. The sorption mechanism of DAAR for Sm(Ⅲ)was examined by using chemical method and IR spectrometry. The coordination bond was formed between oxygen atoms in the functional group of DAAR and Sm(Ⅲ). 相似文献
9.
制备了一系列基于配合物Sm(DBM)3phen的电致发光器件. 研究了其光致发光(PL)和电致发光(EL)性质, 实验结果表明, Sm(DBM)3phen具有良好的电子注入和传输性能以及电致发光性能. 器件ITO/TPD(50 nm)/Sm(DBM)3phen(50 nm)/Alq3(30 nm)/LiF(1.0 nm)/Al的最大亮度和最大效率分别为150 cd/m2和0.72 cd/A, 器件表现为纯Sm3+离子的发光. 相似文献
10.
Addition of HMPA to [Sm[N(SiMe(3))(2)](2)] produces a less reactive reductant in contrast to addition of HMPA to SmI(2). While the [Sm[N(SiMe(3))(2)](2)]-HMPA combination results in a more powerful reductant based on the redox potential, the observed decrease in reactivity is attributed to steric hindrance caused by the nonlabile ligand -N(SiMe(3))(2) and HMPA around the Sm metal. The importance of ligand displacement (exchange) in Sm(II)-HMPA-based reactions and insight into the mechanism of [Sm[N(SiMe(3))(2)](2)]-HMPA and SmI(2)-HMPA reductions are presented. 相似文献
11.
Yang H Jin H Hong B Liu Z Beavers CM Zhen H Wang Z Mercado BQ Olmstead MM Balch AL 《Journal of the American Chemical Society》2011,133(42):16911-16919
The carbon soot obtained by electric arc vaporization of carbon rods doped with Sm(2)O(3) contains a series of monometallic endohedral fullerenes, Sm@C(2n), along with smaller quantities of the dimetallic endohedrals Sm(2)@C(2n) with n = 44, 45, 46, and the previously described Sm(2)@D(3d)(822)-C(104). The compounds Sm(2)@C(2n) with n = 44, 45, 46 were purified by high pressure liquid chromatography on several different columns. For endohedral fullerenes that contain two metal atoms, there are two structural possibilities: a normal dimetallofullerene, M(2)@C(2n), or a metal carbide, M(2)(μ-C(2))@C(2n-2). For structural analysis, the individual Sm(2)@C(2n) endohedral fullerenes were cocrystallized with Ni(octaethylporphyrin), and the products were examined by single-crystal X-ray diffraction. These data identified the three new endohedrals as normal dimetallofullerenes and not as carbides: Sm(2)@D(2)(35)-C(88), Sm(2)@C(1)(21)-C(90), and Sm(2)@D(3)(85)-C(92). All four of the known Sm(2)@C(2n) endohedral fullerenes have cages that obey the isolated pentagon rule (IPR). As the cage size expands in this series, so do the distances between the variously disordered samarium atoms. Since the UV/vis/NIR spectra of Sm(2)@D(2)(35)-C(88) and Sm(2)@C(1)(21)-C(90) are very similar to those of Gd(2)C(90) and Gd(2)C(92), we conclude that Gd(2)C(90) and Gd(2)C(92) are the carbides Gd(2)(μ-C(2))@D(2)(35)-C(88) and Gd(2)(μ-C(2))@C(1)(21)-C(90), respectively. 相似文献
12.
Arvanitidis J Papagelis K Margadonna S Prassides K 《Dalton transactions (Cambridge, England : 2003)》2004,(19):3144-3146
Sm(2.75)C(60) displays large negative thermal expansion behaviour in the temperature range 4.2-32 K at ambient pressure as a result of a quasi-continuous valence change from the larger Sm(2+) towards the smaller Sm(2.3+) ion. Here we use the powder synchrotron X-ray diffraction technique at ambient temperature and elevated pressures to study the compression behaviour in the pressure range 0-6 GPa. An abrupt hysteretic phase transition, accompanied by a dramatic volume decrease (approximately =6.0%) and a change in colour from black to golden was found at approximately =4 GPa induced by a sudden Sm valence transition from +2.3 towards +3. Such behaviour is typical of highly correlated Kondo insulators like SmS and makes Sm(2.75)C(60) the first known molecular-based member of this fascinating class of materials. 相似文献
13.
Damon R. Click Brian L. Scott John G. Watkin 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1095-1096
In the title complex, [Sm(C9H9F5NSi)3(C4H8O)], the Sm metal center is coordinated in a highly distorted tetrahedral geometry by the three N atoms of the amido ligands and by the O atom of the tetrahydrofuran ligand. Principal bond lengths include: Sm—N 2.299 (4), 2.339 (4) and 2.366 (4) Å, and Sm—O 2.446 (3) Å, close Sm?F contacts of 2.536 (3) and 2.556 (3) Å, and an `agostic' Sm?C interaction of 3.154 (4) Å. 相似文献
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《结构化学》1989,(1)
<正> Biaqua-trichloroacetate-samarium dihydrate, [Sm(CCl3COO)3(H2O)2]-2H2O, Mr=707.54, orthorhombic, space group Pnne, with a = 19.158(5), b = 22.176(4), c= 9.798(4)A, Z= 8, V= 4162.7A3.F{000)= 2696,λ(MoKα)=0.71069A, Dx = 2.258 g/cm3, final R=0.061. The title compound has non-molecular structural character, and its structural units Sm(μ-CCl3COO)s/2-(H2O>2 constitute 2-dinensional infinite chains of Sm(μ-CCl3COO)4Sm(μ-CCl3-COO)2Sm.The Sa(Ⅲ) atom in each unit is bound to two O atoms from aqua-molecules and six 0 atoms from six bridging CCl3COO groups (four of which are shared with the SB atom of another unit, two shared with the Sm atom of a third unit) forming a square antiprism. 相似文献
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Maity S Choquette KA Flowers RA Prasad E 《The journal of physical chemistry. A》2012,116(9):2154-2160
Electron transfer from the ground and excited states of Sm[15-crown-5](2)I(2) complex to a series of electron acceptors (benzaldehyde, acetophenone, benzophenone, nitrobenzene, benzyl bromide, benzyl chloride, 1-iodohexane, and 1,4-dinitrobenzene) was investigated in acetonitrile. Electron transfer from the ground state of the Sm(II)-crown system to aldehydes and ketones has a significant inner sphere component indicating that the oxophilic nature of Sm(II) prevails in the system even in the presence of bulky ligands such as 15-crown-5 ether. Activation parameters for the ground state electron transfer were determined, and the values were consistent with the proposed mechanistic models. Since crown ethers stabilize the photoexcited states of Sm(II), the photochemistry of Sm[15-crown-5](2)I(2) system in solution state has been investigated in detail. The results suggest that photoinduced electron transfer from Sm(II)-crown systems to a wide variety of substrates is feasible with rate constant values as high as 10(7) M(-1) s(-1). The results described herein imply that the present difficulty of manipulating the extremely reactive excited state of Sm(II) in solution phase can be overcome through stabilizing the excited state of the divalent metal ion by careful design of the ligand systems. 相似文献
18.
CO(2) inserts into the Sm-S and Sm-Se bonds of [(C(5)Me(5))(2)Sm(mu-EPh)](2) (E = S, Se) to form the first crystallographically characterized (O(2)CEPh)(1-) complexes, [(C(5)Me(5))(2)Sm(mu-O(2)CEPh)](2). These complexes are structurally analogous to [(C(5)Me(5))(2)Sm(mu-O(2)CR)](2) complexes, but they are less soluble. This feature was utilized in the reaction of Me(2)AlCl with [(C(5)Me(5))(2)Sm(mu-O(2)CEPh)](2), which forms crystallographically characterizable [Me(2)Al(mu-O(2)CEPh)](2) complexes. Such complexes could not be isolated from an analogous carboxylate reaction. [(C(5)Me(5))(2)Sm(mu-O(2)CSePh)](2) decarboxylates in THF to form (C(5)Me(5))(2)Sm(SePh)(THF). The loss of CO(2) rather than COSe with formation of (C(5)Me(5))(2)Sm(OPh)(THF) was established by (13)CO(2) studies and independent synthesis of (C(5)Me(5))(2)Sm(OPh)(THF) from (C(5)Me(5))(2)Sm[N(SiMe(3))(2)] and PhOH. 相似文献
19.
以Sm作为填充原子,用熔融法结合放电等离子快速烧结技术(SPS)制备出了单相的SmyFexCo4-xSb12化合物。Rietveld精确化结果表明:所制备的SmyFexCo4-xSb12化合物具有填充式skutterudite结构,Sm的热振动参量(B)比Sb和Fe/Co的大,说明Sm在SmyFexCo4-xSb12化合物中具有扰动效应。热电性能测试结果表明:随着Sm原子填充分数的增加,SmyFexCo4-xSb12化合物的电导率减小;Seebeck系数增加,在填充分数为0.38时达最大值;热导率减小,在填充分数为0.32时最低。Sm0.32Fe1.47Co2.53Sb12化合物在750K时具有最大热电性能指数ZTmax值为0.68。 相似文献
20.
Under mild solvothermal conditions two novel thioantimonates(V) [Sm(en)4]SbS4 x 0.5en (1) and [Sm(en)3(H2O)(micro-SbS4)]infinity (2) were synthesized; the structure of 1 contains discrete [Sm(en)4]3+ and [SbS4]3 ions, while 2 consists of neutral [Sm(en)3(H2O) (micro-SbS4)] one-dimensional chains. 相似文献