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1Author    Jorma HölsäRequires cookie*
 Title    Parametrization of Crystal Field Splittings of the 7 F 7 Levels in Eu 3+ Doped Tetragonal Rare Earth Oxyhydroxides, REOOH:EU 3+ (RE = Y and Lu)  
 Abstract    The luminescence spectra of europium (3 +) doped rare earth oxyhydroxides, REOOH :Eu 3 + (RE = Y and Lu), were studied and analyzed at 77 and 300 K under UV and dye laser excitation. The observed 7 F 0 _ 4 level schemes were simulated with the aid of the phenomenological crystal field theory. The descending symmetry method from C 2v to C s symmetry was used in the simulation. Good results were obtained with C s symmetry simulation which yielded r.m.s. deviations of 6 and 7 cm -1 between the calculated and experimental 7 F 0 _ 4 level schemes for YOOH:Eu 3+ and LUOOH:EU 3+ , respectively. The C 2v simulation was found inadequate to describe the experimental energy level schemes. The even rank crystal field parameters vary only slightly as a function of the host. Comparison with the corresponding values obtained for the monoclinic form of the Eu 3 + doped RE oxyhydroxides reveals significant differences. 
  Reference    Z. Naturforsch. 45a, 173—178 (1990); received October 23 1989 
  Published    1990 
  Keywords    Crystal field, Europium, Rare earth oxyhydroxides 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0173.pdf 
 Identifier    ZNA-1990-45a-0173 
 Volume    45 
2Author    Giorgio Concas, Giorgio Spano, Marzia Carrada, Marco Bettinelli, Adolfo SpeghiniRequires cookie*
 Title    Local Structure of Europium Sites in Oxide Glasses by Nuclear Gamma Resonance  
 Abstract    The symmetry and disorder of the Eu 3+ site was investigated in some phosphate and borate glasses by means of 151 Eu Mössbauer spectroscopy. The quadrupole interaction parameter, which is due to the distortion of the Eu site compared to a cubic symmetry, has been measured together with the asymmetry parameter, which points out the absence of a threefold or fourfold axis of symmetry at the rare earth site. The correlation of the isomer shift with the optical basicity of the glass indicates a covalent component with 6s character in the Eu-0 bond. The axial component of the electric field gradient at the Eu site is also correlated with the optical basicity. 
  Reference    Z. Naturforsch. 54a, 539—544 (1999); received August 5 1999 
  Published    1999 
  Keywords    Europium, Oxide Glasses, Phosphates, Borates, 15 'Eu Mössbauer Spectroscopy 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0539.pdf 
 Identifier    ZNA-1999-54a-0539 
 Volume    54 
3Author    G. Concas, F. Congiu, G. Spano, A. Speghini, K. Gatterer, M. H. BartlRequires cookie*
 Title    Hyperfine Interactions at Lanthanide Sites in Europium Doped Oxide Glasses  
 Abstract    A series of europium doped Na 2 0-B 2 0 3 -Si0 2 , Pb0-Ge0 2 and Zn0-Te0 2 glasses was investi-gated by means of 5l Eu Mössbauer spectroscopy. The distortion of the Eu sites has been evaluated in the Na 2 0-B 2 0 3 -Si0 2 glasses by means of the quadrupolar interaction parameter and the asym-metry parameter; the disorder has been estimated by the line width. The occupancy of the sites in the borosilicate glasses is discussed. The correlation of the isomer shift with the optical basicity of the glass is discussed in terms of the degree of covalence of the Eu-0 bond. 
  Reference    Z. Naturforsch. 55a, 499—506 (2000); received December 14 1999 
  Published    2000 
  Keywords    Europium, Oxide Glasses, Borosilicates, Germanates, 15 'Eu Mössbauer Spectroscopy 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0499.pdf 
 Identifier    ZNA-2000-55a-0499 
 Volume    55 
4Author    G. Concas, C. Muntoni, G. Spano, M. Bettinelli3, A. Speghini3Requires cookie*
 Title    Mössbauer Investigation of Eu3+ Site Occupancy and Eu-O Covalency in Y20 3 and Gd20 3 Nanocrystals  
 Abstract    Samples of nanocrystalline Yj 8Euo.20 3 and G d18Euo20 3 were examined by 151Eu Mössbauer spectroscopy. The degree of covalency of the E u-0 bond has been studied. The spectrum of the cubic Yj gEuo 20 3 sample has been resolved into 2 contributions due to europium in the C3i and C2 sites, for the first time in 151Eu Mössbauer spectroscopy. The degree of covalency and the electric field gradient of the 2 sites has been compared. The occupancy, by the lanthanide ion, of the more and less symmetric sites in the cubic structure of Yj gEuo 20 3 has been investigated and discussed. 
  Reference    Z. Naturforsch. 56a, 267—272 (2001); received November 11 2000 
  Published    2001 
  Keywords    Europium, Yttrium, Oxides, Nanocrystals, 151Eu Mössbauer Spectroscopy 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0267.pdf 
 Identifier    ZNA-2001-56a-0267 
 Volume    56 
5Author    R. Ainer PöttgenRequires cookie*
 Title    EuPdGe -a New Germanide with EuNiGe Type Structure  
 Abstract    The title compound was prepared from the elem ental com ponents in a tantalum tube at 1070 K and investigated by X-ray diffraction of both powder as well as single crystals. The crystal structure was refined from four-circle diffractometer data: P 2 xln, a = 618.1(1), b = 613.6(1), c = 743.9(1) pm, ß = 109.40(1)°, V = 0.2661(1) nm3, Z = 4 ,w R 2 = 0.0536 for 1564 F2 values and 29 variables. EuPdGe crystallizes with the E uN iG e type structure. Both Pd and G e atom s in EuPdGe have three germanium or palladium neighbors, respectively. They form two-dim ensionally infinite [PdGe] polyanions which consist o f corrugated 4.82 nets. These polyanions are separated by the europium atoms. 
  Reference    Z. Naturforsch. 50b, 1181—1184 (1995); received March 1 1995 
  Published    1995 
  Keywords    Germanide, Crystal Structure, X-Ray, Europium 
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 TEI-XML for    default:Reihe_B/50/ZNB-1995-50b-1181.pdf 
 Identifier    ZNB-1995-50b-1181 
 Volume    50 
6Author    Masahiko Matsumiya, Ryuzo TakagiRequires cookie*
 Title    Electrochemical Impedance Spectroscopic Study on Eu 2+ and Sr 2+ Using Liquid Metal Cathodes in Molten Chlorides  
 Abstract    For the pyrochemical reprocessing of spent metallic nuclear fuels in molten salt baths it is important to investigate the behavior of the electrochemically negative elements Eu and Sr, which are significant fission products. Voltammetric and chronopotentiometric studies have shown that the reduction of Eu 2+ and Sr 2+ on liquid Pb cathodes in molten chloride baths at 1073 K follows the alloy formation reaction: Eu 2+ + 2e~ + 3Pb — • EuPb 3 and Sr 2+ + 2e~ + 3Pb — • SrPb 3 . In the present work these alloy formation reactions were studied by electrochemical impedance spectroscopy. Analysis of the spectra showed that the electronic exchange of Eu 2+ /Eu and Sr 2+ /Sr is quasi-re-versible. Moreover, the experimental results allowed the determination of the kinetic parameters of EU 2+ /EU and Sr 2+ /Sr, the diffusion coefficients of these species in molten chloride baths, and also the diffusion layer thickness. 
  Reference    Z. Naturforsch. 55a, 673—681 (2000); received April 25 2000 
  Published    2000 
  Keywords    Alloy Formation Reaction, Europium, Impedance, Liquid Metal Cathodes, Molten Salts, Strontium 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0673.pdf 
 Identifier    ZNA-2000-55a-0673 
 Volume    55 
7Author    Wolfgang RammRequires cookie*
 Title    Die Abhängigkeit der Absorption thermischer Neutronen von ihrer Geschwindigkeit  
 Abstract    Die Herabsetzung der Dichte thermischer Neutronen in der Umgebung eines Absorbers wurde bei Zimmertemperatur und bei 200 °C bestimmt. Daraus' konnte die Abhängigkeit des Einfangquerschnitts von der Energie im thermischen Gebiet, praktisch unabhängig von der Größe des Streuquerschnitts, gefunden werden. Die Messungen wurden mit Bor, 
  Reference    (Z. Naturforschg. 4a, 245—257 [1949]; eingegangen am 8. Mai 1948) 
  Published    1949 
  Keywords    Chlor, Mangan, Eisen, Kobalt, Kupfer, Silber, Cadmium, Samarium, Europium, Gadolinium, Dysprosium und Quecksilber durchgeführt 
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 TEI-XML for    default:Reihe_A/4/ZNA-1949-4a-0245.pdf 
 Identifier    ZNA-1949-4a-0245 
 Volume    4 
8Author    S. A. Kuznetsov, L. Rycerza, M. Gaune-Escard3Requires cookie*
 Title    Electrochemical and Thermodynamic Properties of EuC13 and EuC12 in an Equimolar NaCl-KCl Melt  
 Abstract    The electroreduction o f EuCl3 in an equimolar NaCl-KCl mixture was studied at 973 -1123 K by different electrochemical methods. This reduction of Eu(III) in NaCl-KCl melt occurs via two successive reversible steps involving transfer o f one and two electrons. The diffusion coefficients of Eu(III) and Eu(II) were measured by linear sweep voltammetry and chronopotentiometry. The values found by these methods are in a good agreement. The standard rate constants for the redox reaction Eu(III) + e~ <=> Eu(II) were calculated from cyclic voltammetry data. The sluggish kinetics of this reaction is discussed in terms o f substantial rearrangement of the europium coordination sphere. Special attention was paid to the choice of working electrodes for the study o f electrode reactions. The formal standard potentials E*E u (^ /Ba, E* eU (hr/eu and the formal redox potentials ^*Eu(ni)/Eu(ii) were determined from open-circuit potentiometry and linear sweep voltammetry data. The free Gibbs energy changes for the reaction EuC13(so1) EuCl2(SO i.) + 1/2 Cl2(g.) and the equilibrium constants o f the metal-salt reaction 2Eu(III) + Eu 3 Eu(II) were calculated. The thermodynamics of the formation o f dilute solutions of europium di-and trichloride in an equimolar NaCl-KCl melt were determined. It was shown that electrochemical transient techniques give the possibility o f the determination of the relative partial molar mixing enthalpy of europium trichloride and dichloride in NaCl-KCl melt. 
  Reference    Z. Naturforsch. 56a, 741 (2001); received August 20 2001 
  Published    2001 
  Keywords    Europium, Molten Salts, Kinetics of Electrode Reaction, Formal Standard Potentials, Mixing Enthalpy 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0741.pdf 
 Identifier    ZNA-2001-56a-0741 
 Volume    56