- Preparation, morphology, and luminescent properties of europium-doped nanodispersed scandium sesquioxide
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Scandium sesquioxide-based solid solutions of composition Sc 2 - 2x Eu2x O3 (0.005 ≤ x ≤ 0.05) were prepared by thermolysis of Sc1 - x Eu x (CH 3COO)3 and by reacting mixtures of scandium and europium nitrates with ethylene glycol. Thermal decomposition of Sc1 - x Eu x (CH3COO)3 was found to yield Sc 2 - 2x Eu2x O3 with the shapes of aggregates atypical of the cubic structure of this oxide, and the reaction products of scandium and europium nitrates were found to have a loose spongelike structure. A spectroscopic study showed that Sc2 - 2x Eu2x O 3 and Sc1 - x Eu x (CH3COO) 3 are potential luminescent materials active in the visible spectral region. The tervalent europium in the Sc2 - 2x Eu2x O 3 structure is the source of strong red emission (5 D 0 → 7 F 2) and can be used in fluorescent lamps, colored lightning, and optoelectronic devices.
- Baklanova,Krasil'Nikov,Perelyaeva,Gyrdasova
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- Experimental and theoretical studies of45Sc NMR interactions in solids
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Solid-state 45Sc NMR spectroscopy, ab initio calculations, and X-ray crystallography are applied to examine the relationships between 45Sc NMR interactions and molecular structure and symmetry. Solid-state 45Sc (I = 7/2) magic-angle spinning (MAS) and static NMR spectra of powdered samples of Sc-(acac)3, Sc(TMHD)3, Sc(NO3)3·5H2O, Sc(OAc)3, ScCl3·GH2O, ScCl3·3THF, and ScCp3 have been acquired. These systems provide a variety of scandium coordination environments yielding an array of distinct 45Sc chemical shielding (CS) and electric field gradient (EFG) tensor parameters. Acquisition of spectra at two distinct magnetic fields allows for the first observations of scandium chemical shielding anisotropy (CSA). 45Sc quadrupolar coupling constants (CQ) range from 3.9 to 13.1 MHz and correlate directly with the symmetry of the scandium coordination environment. Single-crystal X-ray structures were determined for Sc(TMHD)3, ScCl3·6H2O, and Sc(NO3) 3·5H2O to establish the hitherto unknown scandium coordination environments. A comprehensive series of ab initio calculations of EFG and CS tensor parameters are in excellent agreement with the observed parameters. Theoretically determined orientations of the NMR interaction tensors allow for correlations between NMR tensor characteristics and scandium environments. Solid-state 45Sc, 13C, and 19F NMR experiments are also applied to characterize the structures of the microcrystalline Lewis acid catalyst Sc(OTf)3 (for which the crystal structure is unknown) and a noncrystalline, microencapsulated, polystyrene-supported form of the compound.
- Rossini, Aaron J.,Schurko, Robert W.
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- Crystal Structure of Sc(CH3COO)3, a Metal(III) Acetate with a Chain Structure
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Sc(acO)3 was obtained from Sc2O3 and (CH3CO)2O or from Sc2(CO3)3 and acetic acid.Recrystallization in water yields hexagonal columns of anhydrous Sc(acO)3.It crystallizes in the space group P63/mcm with the lattice constants a = 791.1(3) pm, c = 886.6(7) pm and z = 2.Sc(acO)3 exhibits a polymeric structure with a linear chain of metal atoms which are connected in each case by three bridging acetato groups.For the Sc atoms results a sixfold coordination in the form of a compressed octahedron with the symmetry D3d and with distances Sc-O = 208.4 pm.The columns of polymeric Sc(acO)3 are arranged like in an ideal hexagonal close packing of cylindrical rods. - Key words: Scandium(III) Acetate, Synthesis, Crystal Structure, Chain Structure
- Fuchs, Robert,Straehle, Joachim
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p. 1662 - 1663
(2007/10/02)
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