- Scandium/Alkaline Metal-Organic Frameworks: Adsorptive Properties and Ionic Conductivity
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Several synthetic approaches have been employed to obtain novel {[ScM(μ4-pmdc)2(H2O)2]·solv}n [EHU1(Sc,M)] (where M = Li, Na; pmdc = pyrimidine-4,6-dicarboxylate; solv = corresponding solvent) compounds. The synthesis method is crucial to determine the type of alkaline that could be hosted in the structure as well as the crystallinity, adsorption performance, and ionic conductivity of the resulting materials. Compared with other synthetic methods, a heat-assisted solvent-free procedure has proven to be the most effective route, giving materials with adsorption capacities close to those expected from GCMC (Grand Canonical Monte Carlo) calculations. Despite the presence of alkaline ions in the framework, the pristine materials exhibit rather low conductivity values of ca. 10-7 S cm-1. The concentration of charge carriers has been increased by means of a doping approach that incorporates divalent transition metal ions to the structure and forces an increase of the alkaline ions, thus raising the ionic conductivity by 1 order of magnitude. Additionally, soaking the samples in solutions containing alkaline salts led to materials possessing an even higher number of carriers achieving conductivity values among the best results reported for MOFs at room temperature, i.e., 4.2 × 10-4 and 9.2 × 10-5 S cm-1 for EHU1(Sc,Li) and EHU1(Sc,Na) obtained by the solvent-free procedure, respectively.
- Cepeda, Javier,Pérez-Yá?ez, Sonia,Beobide, Garikoitz,Castillo, Oscar,Goikolea, Eider,Aguesse, Frederic,Garrido, Leoncio,Luque, Antonio,Wright, Paul A.
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- A Raman Investigation of the Hydration Number of Scandium(III) Ions
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Raman spectra were measured for aqua-Sc3+ ions in aqueous ScCl3 and Sc(ClO4)3 solutions in both the liquid state at room temperature and the glassy state at liquid nitrogen temperature.Four Raman bands, inconsistent with octahedral symmetry, were observed for aqua-Sc3+ ions in the glassy ScCl3 solution.It is concluded that the inner-sphere hydration number of all-aquated Sc3+ ions is other than six, probably seven.
- Kanno, H.,Yamaguchi, T.,Ohtaki, H.
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- Lanthanide-doped Sr2ScF7 nanocrystals: controllable hydrothermal synthesis, the growth mechanism and tunable up/down conversion luminescence properties
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Sr2ScF7:Ln3+ (Ln = Ce, Tb, Eu, Sm, Dy, Er, Tm, Ho and Yb) nanocrystals were firstly synthesized via a one-step hydrothermal route without employing any surfactants. The shape and size of the Sr2ScF7 nanocrystals could be readily tuned from nanorods with 120 nm length and 50 nm width to nanoparticles with a uniform diameter of 15 nm by doping 30% Ln3+ with a larger ionic radius. Furthermore, the influence of pH values, F? sources and different surfactants on the sizes and morphologies (including nanorods, quadrangular microplates, cubes and polyhedrons) of the as-prepared products was systematically investigated and the possible formation mechanism for the products has been proposed. The XRD, SEM, EDS, PL analysis and decay lifetimes were used to characterize the products. For DC photoluminescence, the Sr2ScF7:Ln3+ nanocrystals show the characteristic f-f transitions with emission colors of bluish violet (Ce3+, Tm3+), green (Tb3+, Er3+, Ho3+), blue (Dy3+) and orange (Eu3+, Sm3+) respectively. Under single wavelength 980 nm excitation, the blue UC emissions of Sr2ScF7:Yb3+,Tm3+ nanocrystals at 474 nm due to the 1G4 → 3H6 transition of Tm3+, the green UC emissions of Sr2ScF7:Er3+ nanocrystals at 522/544 nm assigned to the 2H11/2 → 4I15/2/4S3/2 → 4I15/2 transitions and the red UC emissions of Sr2ScF7:Yb3+,Er3+ at 660 nm from 4F9/2 → 4I15/2 transition of Er3+ were observed. Based on the generation of red, green, and blue emissions, the Sr2ScF7:Yb3+,Er3+,Tm3+ nanocrystals could produce multicolor, particularly in the white region (0.320, 0.330) by controlling the doping concentration of Tm3+ in the Sr2ScF7:Yb3+,Er3+,Tm3+ nanocrystals. Controlling the doping concentration of Tm3+ is an effective way of modulating the luminescence properties of Sr2ScF7:Ln3+ by controlling its size and morphology. The as-synthesized phosphors might be potentially applied in the fields of color displays, light, photonics and biological imaging.
- Zhao, Bei,Shen, Dingyi,Yang, Jun,Hu, Shanshan,Zhou, Xianju,Tang, Jianfeng
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- Temperature sensing performance based on up-conversion luminescence in hydrothermally synthesized Yb3+/Er3+co-doped NaScF4phosphors
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NaScF4:Yb3+/Er3+crystals were successfully hydrothermally synthesized using distilled water as a single solvent. The crystal phase and morphology were characterized by XRD and SEM. Compared with organic solvents such as ethanol, ethylene glycol and ether, the molar ratio of Na/F/Sc plays an important role in the synthesis of NaScF4crystals. Morphological control was achieved by changing the types of additives, and the relationship between morphology and luminescence properties was explored. The NaScF4:Yb3+/Er3+phosphors exhibit strong green and red UC emissions under the excitation of 980 nm NIR. Optimal concentrations of Yb3+and Er3+for up-conversion luminescence performance were identified as 10percent and 2percent, respectively. Without any subsequent heat treatment process, the obtained NaScF4:10percentYb3+/2percentEr3+showed good temperature sensitivity. The temperature sensing ability was investigated by employing the dependence of the fluorescence intensity ratio (FIR) of the two thermal coupling energy levels of Er3+(2H11/2→4I15/2and4S3/2→4I15/2) on temperature; the maximum sensitivitySA/SRwas 0.00256 K?1/0.00317 K?1at 548 K, and it increased to 0.00328 K?1/0.00413 K?1after adding EDTA. In addition, an evaluation of temperature uncertainty during temperature measurement was performed, and was found to be 0.073 K and 0.095 K in the presence and absence of EDTA, respectively. Compared with some other reported materials, the obtained material shows a relatively superior temperature sensitivity, which provides new ideas for the improvement of temperature-sensitive materials.
- Hu, Shanshan,Jiang, Li,Mao, Yini,Tang, Jianfeng,Xian, Pengfei,Yang, Jun
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- Extraction of scandium ions by new aminophosphinyl extractants
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Extraction of Sc(III) ions by new aminophosphinyl compounds containing one or two methylenediorganylphosphinyl groups at the nitrogen atom was studied with a target of the development of effective and selective extractants of trace elements. The selection
- Cherkasov,Garifzyanov,Leont'Ev,Davletshin,Koshkin
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- Two Series of New Volatile Rare-Earth Metal Tris(guanidinates) and Tris(amidinates)
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Two series of new volatile, homoleptic lanthanide(III) tris(guanidinate) and tris(amidinate) complexes were synthesized and fully characterized. Treatment of anhydrous rare-earth metal(III) chlorides, LnCl3, with three equiv. of the aziridine-derived lithium guanidinate Li[c-C2H4NC(NiPr)2] (3) afforded the new homoleptic tris(guanidinate) complexes [c-C2H4NC(NiPr)2]3Ln (4) (Ln = Sc, Pr, Nd, Sm, Eu, Ho, Tm) in good yields (68–80 %). In a similar manner, the homoleptic tris(amidinate) complexes [iPrC(NiPr)2]3Ln (6) Ln = Sc, Ce, Pr, Nd, Tb, Dy, Er, Yb) were prepared from LnCl3 and the all-isopropyl-substituted lithium amidinate Li[iPrC(NiPr)2] (5) in a molar ratio of 1:3. Variable-temperature 1H NMR studies of the paramagnetic derivatives 4Pr–4Tm revealed Curie-type behavior. 1H NMR spectroscopic data of complexes 6 indicated severe steric crowding due to the presence of nine isopropyl groups in these molecules. The molecular and crystal structures of eight title compounds (4Sc, 4Pr, 4Nd, 4Sm, 4Eu, 4Ho, 4Tm, and 6Er) were determined through single-crystal X-ray diffraction studies. All complexes 4 exhibit similar molecular structures, comprising distorted octahedral molecular structures with small bite angles. Sublimation temperatures of 4 at 0.05 mbar were determined to be in the range between 151 °C (4Eu) and 194 °C (4Tm), whereas the complexes 6 sublime in the temperature range between 140 °C (6Sc) and 180 °C (6Ce), so that the use of these precursors in future ALD or CVD studies appears feasible.
- Tutacz, Peter,Harmgarth, Nicole,Z?rner, Florian,Liebing, Phil,Hilfert, Liane,Engelhardt, Felix,Busse, Sabine,Edelmann, Frank T.
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- Raman spectroscopic studies of scandium(III) hydration in aqueous solution - About the first hydration sphere of Sc(III) in solution
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It has been shown conclusively that Sc(III) in aqueous perchlorate solution occurs as an hexaaqua cation. The weak, polarized Raman band assigned to the v1(a1g) ScO6 mode of the hexaaqua-Sc(III) ion (Th symmetry for the whole complex ion or Oh symmetry for the ScO6 unit) has been studied as a function of concentration and temperature. The isotropic scattering geometry in R-format was employed in order to measure the true vibrational contribution of the band and account for the Boltzmann temperature factor B and the wavenumber factor v. The v1(a1g)ScO6 mode at 442 cm-1 of the hexaaqua-Sc(III) shifts only 3 cm-1 to lower wavenumbers and broadens about 20 cm-1 for a 60°C temperature increase. The Raman spectroscopic data suggest that the hexaaqua Sc(III) ion is stable in perchlorate solution within the temperature range measured. Besides the polarized component at 442 cm-1, two weak depolarized modes at 295 cm-1 and 410 cm-1 were measured in the Raman effect. These two modes of the ScO6 unit were assigned to v5(f2g) and v2(eg) respectively. The infrared active mode, v3(f1u), was measured to be at 460 cm-1. The wavenumber data confirm the centrosymmetry of the Sc(III)aqua-complex, in opposite to earlier Raman results. These findings are also in contrast to the results found in Sc2(SO4)3 solutions, where sulfate replaces water in the first hydration sphere and forms quite strong sulfato complexes. In ScCl3 solutions weak chloro-complex(es) could be detected. by Oldenbourg Wissenschaftsverlag, Muenchen.
- Rudolph, Wolfram W.
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- Color-tunable and enhanced luminescence of well-defined sodium scandium fluoride nanocrystals
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In this paper, well-defined and regular-shaped Na3ScF 6 nanocrystals (NCs) have been synthesized in high boiling organic solvents 1-octadecene (ODE) and oleic acid (OA), via the thermal decomposition of rare-earth oleate precursors. It is found that highly uniform monoclinic Na3ScF6 NCs with narrow size distribution have been obtained, which can easily be dispersed in cyclohexane solvent to form transparent colloid solutions. Upon 980 laser diode (LD) excitation, the relative up-conversion (UC) emission intensities of different colors in Yb 3+/Er3+, Yb3+/Tm3+ and Yb 3+/Ho3+ doped Na3ScF6 can be tuned by altering the Yb3+ doping concentration, resulting in the tunable multicolor in a wide range. On the basis of the emission spectra and the plot of luminescence intensity to pump power, the UC mechanisms of the co-doped Na 3ScF6 NCs were investigated in detail. Moreover, the UC emission intensities can be significantly improved by coating a layer of Na 3ScF6:Yb3+/Ln3+ shell on Na 3ScF6:Yb3+/Ln3+ cores with respect to that of pure Na3ScF6:Yb3+/Ln3+ core NCs. Furthermore, transparent and UC luminescent NCs/polydimethylsiloxane (PDMS) composites with regular dimensions were also fabricated by an in situ polymerization route. Uniform NCs with a wide variation of luminescence colors will show potential applications in diverse fields.
- Fu, Hongbo,Yang, Guixin,Gai, Shili,Niu, Na,He, Fei,Xu, Jie,Yang, Piaoping
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- [Sc(OH)(H2O)5]2Cl8: Synthesis, structure, and solid-phase thermal transformation
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The reaction of [Sc(OH)(H2O)5]2Cl 4 ? 2H2O in isopropanol with 4,4-Bipy in CHCl 3 produced a crystalline compound, which was identified as [H 4(4,4-Bipy)3][Sc(OH)(H2O)5] 2Cl8 (I) by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In the structure of compound I, the three protonated diimine molecules form a centrosymmetric trimer via N.N hydrogen bonds. The polyhedron around the Sc atom is an octahedron with one split vertex. The excursion of the Sc atom from the plane formed by the oxygen atoms (water molecules) toward the hydroxo bridges is 0.5 ?. The thermolysis of compound I generates ScCl3, whereas the final decomposition product of the precursor dimer is ScOCl.
- Ilyukhin,Dobrokhotova,Petrosyants
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- An unexpected electro-luminescent properties of scandium(III) heteroaromatic 1,3-diketonate complex
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A novel complex of Sc(III) with pyrazole substituted 1,3-diketone (1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione) was synthesized and characterized by X-ray diffraction, nanotechnology-assisted laser desorption/ionisation time-of-flight mass spectroscopy (NALDI-TOF-MS) and NMR spectroscopy, including 45Sc NMR. The first sample of organic light-emitting diode (OLED) based on heteroaromatic Sc(III) 1,3-diketonate as an active layer was fabricated and tested. The maximum intensity of yellowish-green electroluminescence (530-560 nm) was equal to 40 cd/m 2 and turn-on voltage was about 4.5 V. Further device modification and ligand structure optimization can lead to a better performance of such materials for OLEDs.
- Taydakov, Ilya,Vaschenko, Andrey,Strelenko, Yuri,Vitukhnovsky, Alexey
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- Changes of vibrational modes upon melting solid Cs2NaScCl6, Cs3ScCl6, Cs3Sc2Cl9 and ScCl3
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Raman spectra of Cs2NaScCl6, Cs3ScCl6, Cs3Sc2Cl9 and ScCl3 compounds have been measured from 25°C to temperatures above their melting points. The vibrational modes of the discrete species ScCl63- and Sc2Cl93- in the solids are transferred upon melting into the liquid and participate in an equilibrium involving ScCl4-. The spectra of solid ScCl3 are dominated by the vibrational modes of a triple layer of ions consisting of edge-sharing ScCl63- octahedra. Two main bands are seen in the melt spectra which infer a molecular liquid but a rather complex melt structure is suggested by the overall physicochemical data.
- Zissi,Papatheodorou
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- Aggregates of complexes [Sc(H2O)4(NCS) 2]+ and [Sc(H2O)2(NCS) 4]- with 18-crown-6
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The compounds [Sc(H2O)4(NCS)2][Sc(H 2O)2(NCS)4] ?2(18C6) (I) and [Sc(H 2O)4(NCS)2][Sc(H2O) 2(NCS)4] ? 3(18C6) ? H2/su
- Ilyukhin,Petrosyants
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- Thermodynamic study of the rare earth vapour complexes: ScAl2Cl9 and YAl2Cl9
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In all previous publications dealing with LnAlnCl3n+3 (Ln = rare earth elements), the LnAl3Cl12 complex is established to be the main vapour complex in the temperature range 500-900 K. Here we present results fr
- Wang, Zhi-Chang,Wang, Lin-Shan,Gao, Rong-Jie,Su, Yi
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- One-step surfactant-free synthesis of KSc2F7 microcrystals: controllable phases, rich morphologies and multicolor down conversion luminescence properties
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Homogeneous KSc2F7 microcrystals with controlled and abundant morphologies were prepared by a one-step hydrothermal route without employing any templates or surfactants. Particularly, uniform and well-defined KSc2F7 crystals with rod, sheet, flower-like, thin rectangular, xylitol-like and thin plate morphologies were achieved by manipulating the different environments of crystal growth, such as increasing the concentration of F-, changing pH and adding different surfactants. In addition, a phase transformation from monoclinic ScF3 to orthorhombic KSc2F7 was observed at different molar ratios of F/Sc and pH values, respectively. A more interesting thing is that the KSc2F7 crystals doped with 5% Ln3+ (Ln = La, Ce, Sm, Eu, Gd, Tb and Lu) showed rich morphologies and various sizes. The obtained KSc2F7:Ln3+ products showed multicolor emission with red (Eu3+), green (Tb3+) and blue (Ce3+), respectively. And the best emission conditions for KSc2F7 crystals are F/Sc/K = 3.5:1:3, pH = 7 and without any surfactants. The synthetic KSc2F7:Eu3+/Tb3+/Ce3+ phosphors may potentially be used for multicolor illumination and displays.
- Xiong, Jie,Yu, Jie,Zhang, Yufeng,Xia, Wenpeng,Hu, Shanshan,Zhang, Yanfei,Yang, Jun
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- Synthesis and characterization of paramagnetic lanthanide benzyl complexes
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The organometallic chemistry of paramagnetic lanthanides (Ln, from Ce to Yb) is far less developed compared to that of their diamagnetic counterparts (Sc, Y, La, and Lu). Lack of available starting materials and characterization methods are the major obst
- Huang, Wenliang,Upton, Brianna M.,Khan, Saeed I.,Diaconescu, Paula L.
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supporting information
p. 1379 - 1386
(2013/05/09)
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- Structural characterization of methanol substituted lanthanum halides
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The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(μ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75·5.25(MeOH)]+0.25 [LaBr3.25·4.75(MeOH)]-0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(μ-Cl)]2 (6) and [La(MeOH)9](I)3·MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4-6 were slightly higher in comparison to their hydrated counterparts.
- Boyle, Timothy J.,Ottley, Leigh Anna M.,Alam, Todd M.,Rodriguez, Mark A.,Yang, Pin,Mcintyre, Sarah K.
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p. 1784 - 1795
(2010/07/03)
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- A systemic study of stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by alkaline chlorides as complex former
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A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by the vapor complexes KLnCl4 and NaLnCl4 (Ln = Sc, Y and La-Lu) used NaCl and KCl as complex former, respectively. The results showed that the SC-CVT characteristics are similarly for NaCl and KCl as complex former, the main deposition temperature of the rare earth chlorides LnCl3 is in the increasing order ScCl3 3 3, and then with a systematically decreasing trend from the early lanthanide chlorides to the end one. The results also showed that the total transported amount of the produced chlorides is YCl3 > ScCl3, and they are much higher than that of most lanthanoid chlorides. For lanthanoids, the total transported amount of chloride increases systematically from the early lanthanoid chlorides to the end one except for EuCl3 and GdCl3 mediated by KCl and NaCl as complex former, respectively, which showed the divergence effect of Gd in the total transport efficiency. But there are some differences in SC-CVT characteristics of pure rare earth oxide mediated by KCl and NaCl as complex former, that is the main deposition temperature region for the same rare earth element was lower for KCl than that for NaCl as complex former except for LaCl3, CeCl3, YbCl3 and LuCl3, while the total transport amount of rare earth chloride for KCl as complex former is higher than that for NaCl except for LaCl3 and EuCl3. More over, the discussion was carried out for Sc and Y on the one hand and the lanthanides contain 4f electron as another hand based on the 4f electron hybridization assumption. Further more, the transport characteristics of rare earth oxides with alkaline chlorides as complex former in this study were compared to that with AlCl3 as complex former.
- Sun, Yan-Hui,He, Peng,Chen, Hua-Ni
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p. 352 - 358
(2008/10/09)
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- Comparative study of the mutual separation characteristics for binary mixed oxides Er2O3-Ln2O3 (Ln = Sc, Y, La, Nd, Sm, Gd and Ho) mediated by vapor complexes KLnCl4
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Mutual separation characteristics for a series of rare earth elements Sc, Y, La, Nd, Sm, Gd, Ho and Er from their binary oxide mixtures Er 2O3-Sc2O3, Er2O 3-Y2O3, Er2O3-La 2O3, Er2O3-Nd2O 3, Er2O3-Sm2O3, Er 2O3-Gd2O3 and Er2O 3-Ho2O3 has been investigated using a stepwise chlorination-chemical vapor transport (SC-CVT) reaction mediated by vapor complexes KLnCl4. The total transported yield of the chlorides produced from the oxide mixtures was in the order of ErCl3 > ScCl3, ErCl3 > YCl3, ErCl3 > LaCl3, ErCl3 > NdCl3, ErCl3 > SmCl3, ErCl3 > GdCl3 and HoCl3 > ErCl3, and the total separation factors are 13.0 for Er:Sc, 1.49 for Er:Y, 1.48 for Er:La, 1.15 for Er:Nd, 2.33 for Er:Sm, 2.72 for Er:Gd and 1.10 for Ho:Er. The largest separation factors 1213.8 for Er:Sc, 6.37 for Er:Y, 189.3 for Er:La, 100.6 for Er:Nd, 105.7 for Er:Sm, 27.8 for Er:Gd and 1.14 for Er:Ho in the lower temperature region, while 102.7 for La:Er, only 14.3 for Nd:Er, 16.7 for Sm:Er, 4.0 for Gd:Er and 2.04 for Ho:Er in the higher temperature region were observed, respectively. The results showed the obvious divergence effect of Gd both in the largest separation factors, the total separation factors and total transport efficiency. Furthermore, the results were discussed on the difference of ionic radius of Sc and Y on the one side and the lanthanoid elements of La, Nd, Sm, Gd, Ho and Er on the other hand, and verified that the ionic radius is one of the decisive factors only for lanthanide elements, not for Sc and Y.
- Sun, Yan-Hui,Chen, Zhen-Fei,Hu, Sheng-Liang
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p. 175 - 180
(2008/10/09)
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- Fullerides: Heterometallic superconductors with composition M2M′C60 (M = K, Rb; M′ = Yb, Lu, Sc)
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One- or two-step reactions of potassium and rubidium fullerides with composition Mk C60 (M = K, Rb; k = 3-6) and K 6C60 + m K mixtures (m = 1, 3) with anhydrous salts M′Cl3 (M′ = La, Pr, Nd, Sm, Gd, Tb, Yb, Lu, Y, Sc) and YbI2 in a toluene-THF medium afforded heterometallic fullerides M3- n M′n C60 (n = 1-3). Among these compounds, substituted fullerides with composition M2M′C60 (M′ = Yb, Lu, Sc) display superconducting properties with critical temperatures of 14-20 K.
- Bulychev,Lunin,Kul'bachinskii,Shpanchenko,Privalov
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p. 1686 - 1692
(2007/10/03)
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- Ab initio calculation of the tetracarbonatoscandate-ion in Na5[Sc(CO3)4] · 2 H2O. Single crystal structure determination, vibrational spectra, and thermal decomposition
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Normal modes of the tetracarbonatoscandate-ion, [Sc(CO3)4]5-, were determined by ab initio calculations and were compared with experimental data of Infrared- and Raman-spectra of the compound Na5[Sc(CO3)4] · 2 H2O. A necessary redetermination of the structure with single crystal x-ray diffraction data (tetragonal, P421c (Nr. 114), Z = 2, a = 746,37(4) pm, c = 1157,0(2) pm, VEZ = 644,5(1) 106 pm3) allows the discussion of existing hydrogen bonds. Determination of the thermal behaviour indicates a two-stage decomposition reaction, but no corresponding intermediate could be isolated. WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001.
- Adam, Arnold
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p. 2023 - 2031
(2008/10/08)
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- Comparative study for stepwise chlorination-chemical vapor transport characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by the vapor complexes LnAlnCl3n+3
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A systematic study has been carried out for the stepwise chlorination-chemical vapor transport (SC-CVT) characteristics of pure rare earth oxides from Sc2O3 to Lu2O3 mediated by the vapor complexes LnAlnCl3n+3 (where Ln = rare earth elements) under identical conditions. The results show that the total transported amount of the produced chlorides is the highest for YCl3; it is also high for ScCl3, but low for LaCl3, and then increases systematically from the early lanthanide chlorides to the end lanthanide chlorides except CeCl3, EuCl3 and GdCl3. The results also show that the main deposition temperature of the chlorides is in the increasing order ScCl3 3 3 and then with a systematically decreasing trend from the early lanthanide chlorides to the end lanthanide chlorides. Based on the literature data for the solid complexes LnAl3Cl12 and LnAl3Br12, a similar coordination structure assumption is introduced for the vapor complexes LnAl3Cl3n+3 from Ln = Sc to Ln = Lu with the same stoichiometry to explain the SC-CVT characteristics of the pure rare earth oxides from Sc2O3 to Lu2O3 using a 4f electron hybridization assumption.
- Wang, Zhi-Chang,Sun, Yan-Hui,Guo, Lei
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p. 109 - 113
(2008/10/08)
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- A structural variant to the NaErCl4/α-NiWO4 type for ternary rare-earth halides NaMCl4: Synthesis and crystal structure of NaLuCl4
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Single crystals of NaLuCl4 (orthorhombic, Pbcn (Nr. 60), Z = 4, a = 618.6(1) pm, b = 1592.2(2) pm, c = 657.0(1) pm) were grown for the first time from the binary components using the Bridgman technique. The crystal structure may be derived from a hexagonally closest packing of Cl- spheres with one half of all octahedral sites occupied by the cations Na+ and Lu3+, respectively. The close relation of the structure to that of NaErCl4 (α-NiWO4) is discussed. NaScCl4 was found to be isotypic to NaLuCl4. Johann Ambrosius Barth 1996.
- Wickleder, Mathias S.,Güdel, Hans U.,Armbruster, Thomas,Meyer, Gerd
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p. 785 - 789
(2008/10/09)
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- Standard Enthalpy of Formation of Crystalline Scandium Trichloride
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The enthalpies of solution of scandium metal and crystalline scandium trichloride in HCl*25.59H2O and HCl*25.73H2O, respectively, were measured at 298.15 K in an isothermic-shell solution calorimeter (an LKB-8700 unit).The results are used to calculate the standard enthalpy of formation of crystalline scandium trichloride, ΔfH0(ScCl3, c, 298.15 K) = -944.8 +/- 0.6 kJ/mol.
- Furkalyuk, M. Yu.,Leonidov, V. Ya.,Goryushkin, V. F.
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p. 2029 - 2031
(2007/10/03)
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- Crystal Structure of ScCl3 Refined from Powder Neutron Diffraction Data
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The crystal structure of ScCl3 has been refined from high-resolution powder neutron diffraction data. The structure is of the BiI3 type, and consists of two-dimensional ScCl3 layers. A slight deformation of the ScCl6 coordination octahedron is rationalized on the basis of the different surroundings of the faces of the octahedron. The interatomic distances are discussed in light of crystal structure data for reduced scandium chlorides.
- Fjellvaeg, Helmer,Karen, Pavel
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p. 294 - 297
(2007/10/02)
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- Rate and mechanism of ligand exchange of tris(acetylacetonato)scandium(III) in acetonitrile
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Tris(acetylaceotnato)scandium(III) undergoes ligand exchange with the enolate form of acetylacetone in CD3CN at 30-74°C. The observed first-order rate constant, obtained by the 1H NMR method, is expressed by k0 = k1′[enol] + k2′ at [complex] ? 0.05 M, [Hacac] = 0.19 - 0.58 M, and [H2O] = 0.026-0.26 M; k1′ = 52 ± 3 M-1' s-1 and k2′ = 1.5 ± 0.9 s-1 at 56°C. No water catalysis was observed. The k2′ term is minor in the concentration region. The ΔH? and ΔS? values for k1′ are 36 ± 5 kJ mol-1 and -105 ± 16 J K-1 mol-1, respectively. The deuterium isotope effect k1′(H)/k1′(D) was significant (ca. 5). The Ia mechanism is assigned to the rate-determining formation of an intermediate containing a one-ended acac- and a unidentate Hacac in the enol form.
- Hatakeyama, Yoshihiro,Kido, Hiroaki,Harada, Masayuki,Tomiyasu, Hiroshi,Fukutomi, Hiroshi
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p. 992 - 996
(2008/10/08)
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- Multinuclear magnetic resonance study of tris(cyclopentadienyl)scandium: A fluxional dimer with bridging cyclopentadienyl groups
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(C5H5)3Sc is known to be associated via bridging cyclopentadienyl groups in the solid state, but hitherto nothing was known as to the nature of the compound in solution. 1H NMR studies of the compound in THF show that it exhibits two fluxional processes. The first process observed on cooling is an exchange between the π and σ-bonded rings. The second process, which can only be slowed and not completely stopped on the NMR time scale, is a metallotropic 1,5-shift of the Cp2Sc moiety around the σ-bonded cyclopentadienyl ligand. The existence of only one species in THF, over the temperature range +30 to -80°C is shown by 45Sc NMR. In toluene, however, the exchange between σ and π-bonded cyclopentadienyl ligands is complicated by the onset of dimer formation via bridging cyclopentadienyl groups at low temperature. The presence of two different scandium environments at low temperature is shown by variable-temperature 45Sc NMR spectra.
- Bougeard, Peter,Mancini, Mary,Sayer, Brian G.,McGlinchey, Michael J.
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- Bonding in transition-metal tetrahydroborates: A multinuclear magnetic resonance study of (C5H5)2Sc(BH4) and Sc(BH4)3 and some comments on the isolobality of BH4-, halide, and η5-C5H5- groups
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(C5H5)2Sc(BH4) has been synthesized and shown to contain a triply bridged tetrahydroborate moiety. Multinuclear magnetic resonance data (1H, 11B, and 45Sc) are reported for (C5H2)2Sc(BH4) and for Sc(BH4)3; double- and triple-resonance experiments have allowed the evaluation of all the coupling constants. It is shown that there is no exchange of ring and borohydride protons in (C5H5)2Sc(BH4) in toluene-d8 at elevated temperature as has been claimed for (C2H5)2Zr(BH4)2. In this light, the proposed exchange process has been reinvestigated for (C5D5)2Zr(BH4)2 with use of 2H NMR. The structures of the known main-group and transition-metal borohydrides are rationalized in terms of a correlation between the number of bridging hydrogens and the number of vacant metal orbitals of suitable energy and symmetry. Finally, the similarities in bonding patterns of chloride, tetrahydroborate, and cyclopentadienide groups are analyzed with use of the concept of isolobality.
- Mancini, Mary,Bougeard, Peter,Burns, Robert C.,Mlekuz, Michael,Sayer, Brian G.,Thompson, J. Ian A.,McGlinchey, Michael J.
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p. 1072 - 1078
(2008/10/08)
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- 2-Dialkylaminobenzyl and 2-dialkylaminomethylphenyl derivatives of selected transition metals
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Transition metal compounds of the formulae wherein M1 is scandium, yttrium, chromium, or rare earth metal, and A is 2-dialkylaminobenzyl or 2-dialkylaminomethylphenyl, or a lower alkyl derivative thereof, wherein M2 is Cr or Mo and wherein M3 is Ti, Zr or Hf Are useful as components of coordination catalysts for olefin polymerization. Lithium compounds of the formula LiA are intermediates used in preparing the above compounds. All of the above compounds are also useful as oxygen-scavenging agents.
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