Ln Eu Research Articles

Structure and optical properties of glasses in systems ZrF4―BiF3―BaF2―PbF2―LnF3

New fluoride glasses in the ZrF4―BaF2―BiF3―LnF3 (Ln―Eu, Er, Yb, Nd) system have been produced. The structure and optical properties of glasses have been investigated on the basis of the analysis of IR and inelastic light scattering spectral data. Variations of the composition of fluorozirconate systems through addition of BiF3 components and partial substitution of Ba2+ by Pb2+ did not result in radical changes in the structure of glass networks. Doping of glasses with rare earth elements resulted in radical changes of their low-frequency inelastic scattering spectra that were caused by the rare earth elements photoluminescence contribution. The presence of this contribution was used to establish the fact of glass luminescence itself and to obtain the information on the effect of the glass composition on some photoluminescence parameters.

Solvothermal synthesis, structure and characterization of 1D chain and 2D layered rare earth sulfates in the presence of cyclic diamines

Abstract Three new rare earth sulfates were solvothermally synthesized and characterized by X-ray diffraction, elemental analysis, thermogravimetric, and photoluminescent studies. Compounds [(NH4)(C6N2H12)][Ln(SO4)3] (Ln Eu, 1; Gd, 2) were synthesized in the solvent of DMA with 1,4-diazabicyclo-[2,2,2]-octane (DABCO) as a structure-directing agent (SDA), which are isomorphous and adopt a two-dimensional layered structure with 8-membered rings made of LnO8 polyhedra and SO4 tetrahedra. The protonated DABCO molecules lie between the layers while the ammonium cations are located within the layers. Compound [(C4N2H12)1.5][Er(SO4)3(H2O)] (3) was synthesized in the mixed solvent of water and ethanol with piperazine (PIP) as a SDA. The structural analyses showed that 3 is constructed from ErO9 polyhedra and SO4 tetrahedra to form a one-dimensional chained structure with edge-sharing 4-membered rings. The protonated PIP molecules and coordination H2O molecules form extensive intra- and inter-chain hydrogen bonding to generate a 3-dimensional supramolecular network. The three compounds exhibit good thermal stability. Compound 1 exhibits intense red luminescence upon excitation owing to the Eu3+ ion.

Rare earth β-NaGdF 4 fluorides with multiform morphologies: Hydrothermal synthesis and luminescent properties

In this paper, the synthesis of rare earth fluoride β-NaGdF 4 with multiform morphologies via a facile hydrothermal method has been fulfilled. The phases and shapes of the products can be tuned by changing the experimental parameters, including F − source and pH value of mother liquor. The morphologies for the products range from submicrorods, submicrospheres, dumbbell-like nanorods, cobblestone-like particles to aggregates constructed from nanoparticles. The results indicate that F − source and pH value play a critical role in determining the morphologies of the final products. Additionally, we investigate the photoluminescence (PL) properties of Ce 3+/Ln 3+ (Ln Eu, Tb and Dy) codoped down-conversion (DC) and Yb 3+/Er 3+ (Tm 3+, Ho 3+) codoped up-conversion (UC) in β-NaGdF 4 host lattices. In the process of DC photoluminescence, energy transfer has occurred. This energy transfer occurs through the energy migration process like S → Gd 3+ → (Gd 3+) n → A (S represents the sensitizer and A represents the activator) and the Gd 3+ plays an intermediate role in the process.

Synthesis, structures and physical properties of new 3D lanthanide coordination polymers constructed from 1,2,4,5-benzenetetracarboxylic acid

A series of new 3D coordination polymers Ln 2(BTC) 1.5(H 2O)(DMSO) (Ln Eu( 1), Gd( 2), Tb( 3), Dy( 4), Ho( 5)) (H 4BTC = 1,2,4,5-benzenetetracarboxylic acid) have been solvothermal synthesized by the reactions of lanthanide ions with 1,2,4,5-benzenetetracarboxylic acid in a DMSO/H 2O solution. These compounds possess the same 3D architectures based on dinuclear lanthanide SBUs {Tb 2O 4} linked by BTC 4− anions and exhibit unprecedented 3D topological nets. Compounds 1 and 3 are strong luminescent materials which display characteristic Eu 3+ and Tb 3+ emission bands in the visible region. The magnetic properties of 2– 5 have also been investigated through the measurement of their magnetic susceptibilities over the temperature range of 2–300 K.

FT-IR and fluorometric investigation of rare-earth and metal ion solvation Part 16. Solid state and solution study of acetonitrile-coordinated lanthanid solvates [Ln(CH 3CN) 9](AlCl 4) 31

The CH 3CN coordinated lanthanide solvates [Ln(CX 3CN) 9(AlCl 4) 3 have been studied by means of luminescence (XH,D; LnEu, Tb) and FT-IR spectroscopy (XH; LnLa, Nd, Gd, Er, Lu). High resolution luminescence spectra, recorded at 77 K, of the [Eu(CH 3CN) 9(AlCl 4) 3 microcrystalline compound, show the Eu III ion located in one unique coordination site with a local symmetry close to D 3 h . The same local structure is preserved in Eu-doped La and Dg solvates, pointing to an isostructural series of compounds. The lifetime of the Eu( 5D 0) level amounts to 5.07 ms in the deuterated solvate. The tricapped trigonal prismatic geometry is lost in 0.01 M solutions in anhydrous acetonitrile and propylene carbonate. Analysis of the 3D 0«r 7F 0 transition points to the presence of at least two different species in equilibrium. Vibrational spectra evidence a sizable Ln-acetonitrile interaction substantiated by the shifts of the v 2 and v 3+ v 4 vibrations which increase lienarly with the increase in electronic density of the lanthanide ions and which are identical to those observed for lanthanide perchlorate and nitrate solutions under the same experimental conditions. This means that the Ln-acetonitrile interaction is mainly governed by electrostatic factors. In mixed propylene carbonate-acetonitrile solutions of [La(CH 3CN) 9](AlCl 4) 3 complexes, lanthanum ions are preferentially solvated by propylene carbonate molecules for R=[CH 3CN] t /[Ln III ] t ,⩽50. For R=100, four acetonitrile molecules are bonded to the lanthanum ion.

Preparation and Crystal Structures of Two Dimeric Lanthanoid(III) Complexes Containing Pyridinioacetate and 2,2'-Bipyridine Ligands:[Ln2( bpy )2( pybet )4(H2O)4] ( bpy )3(ClO4)6.H2O (Ln = Eu and Tb)

Two dimeric lanthanoid (III) complexes, [Ln2( bpy )2( pybet )4(H2O)4] ( bpy )3(ClO4)6.H2O ( bpy = 2,2′-bipyridine, pybet = pyridinioacetate, and Ln Eu and Tb), have been prepared and characterized by X-ray crystallography. The complexes are isostructural, each comprising a quadruply carboxylato -bridged, centrosymmetrical dimeric cation, six perchlorate anions, three uncoordinated bpy molecules and a lattice water molecule. Each Ln ion is surrounded in a distorted square-antiprismatic environment by four carboxylato oxygen atoms, two nitrogen atoms of the bidentate bpy ligand and two aqua ligands . The Ln-O bond lengths range from 2.33 to 2.44 Ǻ, and Ln-N bond lengths from 2.55 to 2.64 Ǻ. The uncoordinated bpy molecules are linked to the aqua ligands by hydrogen bonds.

Zur Elektronenstruktur metallorganischer verbindungen der f-Elemente : XXXIV. Ist der N, N′-bis(trimethylsilyl)benzamidinato-Ligand im Falle von Lanthanoid-Zentralionen ein elektronisches Äquivalent zum η 5-Cyclopentadienyl-Liganden?

Magnetic data and the results of low temperature absorption, luminescence and magnetic circular dichroism spectra of 4-methoxy-substituted lanthanide ( III)tris[ N, N′-bis(trimethylsily)benzamidinates [(MeOBA) 3Ln; Ln  Eu ( 1), Pr ( 2)], and of adducts derived from tris(η 5-cyclopentadienyl)-europium( III) [CP 3EuX; X  CNC 6H 11 ( 3), THF ( 4)] are reported. In case of 1, 3 and 4 the 151Eu Mössbauer spectra also were recorded. On the basis of the optical measurements the truncated crystal field (CF) splitting patterns of 1 and 2 were derived. The parameters of an empirical Hamiltonian were fitted to the experimentally derived splitting patterns. The parameters obtained suggest that the BA ligand may be considered to a certain extent as an electronic equivalent to the Cp ligand in case of Ln central ions with small electron affinity. In case of central ions with higher oxidation power such as Eu 3+, the BA ligand behaves in a conventional manner. The Cp ligand, however, causes unusual physical properties which cannot be explained on the basis of an Eu 3+, central ion which is surrounded by three Cp ligands.