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Bad Münster am Stein-Ebernburg, Germany

Plonczak P.,Technical University of Denmark | Joost M.,Institute For Anorganische Und Analytische Chemie | Hjelm J.,Technical University of Denmark | Sogaard M.,Technical University of Denmark | And 2 more authors.
Journal of Power Sources | Year: 2011

Abstract: A multiple spin-coating deposition procedure of Ce 0.9Gd0.1O1.95 (CGO) for application in solid oxide fuel cells (SOFCs) was developed. The thin and dense CGO layer can be employed as a barrier layer between yttria stabilised zirconia (YSZ) electrolyte and a (La, Sr)(Co, Fe)O3 based cathode. The decomposition of the polymer precursor used in the spin-coating process was studied. The depositions were performed on anode supported half cells. By controlling the sintering temperature between each spin-coating process, dense and crack-free CGO films with a thickness of approximately 1 μm were obtained. The successive steps of dense layer production was investigated by scanning electron microscopy. X-ray diffraction was employed to monitor the crystal structure of the CGO layer sintered at different temperatures. The described spin coated barrier layer was evaluated using an anode supported cell with a composite cathode made of La 0.58Sr0.4Co0.2Fe0.8O3 (LSCF) and Ce0.9Gd0.1O1.95. The developed CGO layer, was sufficient to restrain reactions between the perovskite based electrode and the electrolyte. © 2010 Elsevier B.V.

Heymann G.,University of Innsbruck | Riecken J.F.,Institute For Anorganische Und Analytische Chemie | Johrendt D.,Ludwig Maximilians University of Munich | Rayaprol S.,Institute For Anorganische Und Analytische Chemie | And 2 more authors.
Dalton Transactions | Year: 2013

The oxidation of an intermetallic phase under high-pressure/high- temperature conditions led to the synthesis of Ce4Ag 3Ge4O0.5 exhibiting [OCe2Ce 2/2] tetrahedral chains, in which the oxygen atoms statistically occupy the tetrahedral centres. Starting from a 1:1:1 CeAgGe precursor (NdPtSb type), a multianvil high-pressure/high-temperature experiment at 11.5 GPa and 1250-1300 °C revealed Ce4Ag3Ge4O 0.5, crystallizing in the space group Pnma with the following lattice parameters: a = 2087.3(4), b = 439.9(1), and c = 1113.8(2) pm. Magnetic measurements showed Curie-Weiss behavior above 100 K with an experimental magnetic moment of 2.42 μB per Ce atom, close to the value for the free Ce3+ ion, clearly indicating trivalent cerium in Ce 4Ag3Ge4O0.5. Full potential GGA+U band structure calculations resulted in metallic properties and a magnetic ground state with one unpaired 4f-electron per cerium in agreement with the experiments. © 2013 The Royal Society of Chemistry.

Zeng Z.,Institute For Physikalische Chemie | Matuschek D.,Organisch Chemisches Institute | Studer A.,Organisch Chemisches Institute | Schwickert C.,Institute For Anorganische Und Analytische Chemie | And 2 more authors.
Dalton Transactions | Year: 2013

Hybrid materials, in which stable organic radical cations are intercalated into layered inorganic host materials, can be successfully synthesized via an ion exchange reaction in a layered fluoromica clay, to yield recyclable heterogeneous catalysts for oxidation of various alcohols. We have conducted systematic synthetic and structural studies on the intercalation of the radical cations 4-(diethylmethylammonium)-2,2,6,6-tetramethylpiperidin-1-oxyl (DEMTEP), 1-[2-(4-amino-2,2,6,6-tetramethyl-1-piperidinyloxyl)-2-oxoethyl] -1′-methyl-4,4′-bipyridinium (VIOTEP), and 2-(3-N-methylpyridinium)- 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide (m-MPYNN) into a synthetic fluoromica clay named Somasif® ME 100, Na2xMg 3.0-xSi4O10(FyOH1-y) 2 (x = 0.33, y = 0.98). The guest-host interactions in these intercalation compounds have been characterized by X-ray powder diffraction and solid-state NMR of the constituent nuclei (23Na, 19F, and 29Si) of the Somasif structure. The intercalation process can be conveniently monitored using 23Na MAS-NMR. Guest-guest interactions have been probed by magnetic susceptibility measurements as well as EPR and 1H MAS NMR experiments. The 1H MAS-NMR line widths and chemical shifts probe modifications in the electron spin density distributions and/or intermolecular interactions between the electron spins of the guest species. Despite these indications of weakly interacting spins, magnetic susceptibility measurements are consistent with the near-absence of cooperative magnetism. The VIOTEP and DEMTEP inclusion compounds demonstrate catalytic activity for the oxidation of benzyl alcohol, using NaOCl as a co-oxidant. Although the radical ion species is partially leached out under these conditions (ionic exchange with Na+ in solution) the catalytic activity remains for up to 40 subsequent cycles. Fully leached materials can be regenerated by catalyst re-loading and this process can be conveniently monitored by X-band EPR spectroscopy. © 2013 The Royal Society of Chemistry.

Erdmann M.,University of Munster | Rosener C.,Institute For Anorganische Und Analytische Chemie | Holtrichter-Rossmann T.,University of Munster | Daniliuc C.G.,University of Munster | And 5 more authors.
Dalton Transactions | Year: 2013

The vicinal frustrated P/B Lewis pair (FLP) Mes2PCH 2CH2B(C6F5)2 reacts with 9-borabicyclo[3.3.1]nonane (9-BBN) by C6F5vs. H exchange at boron to give the new [B]-H functionalized FLP Mes2PCH 2CH2B(H)(C6F5) (4) and 9-C 6F5-BBN. The latter was characterized as an isonitrile adduct by X-ray diffraction. The new FLP 4 forms an adduct with pyridine and it undergoes clean hydroboration reactions with 1-pentyne or added styrene or dimesitylvinylphosphane. The products formed stable adducts with pyridine; two such examples were also characterized by X-ray crystal structure analysis. A similar alkyl vs. hydrogen exchange was observed upon treatment of an Al/N based Lewis pair, iBu2Al-(Me3Si)C=C(H)-N(CH2CH 2)2NMe (14), with 9-BBN. © 2013 The Royal Society of Chemistry.

Feldmann K.-O.,Institute For Anorganische Und Analytische Chemie | Weigand J.J.,Institute For Anorganische Und Analytische Chemie
Angewandte Chemie - International Edition | Year: 2012

Accessible complexity: Polyphosphorus frameworks [R 4P 4pyr] + and [R 6P 7] + (R=Cy, Ph; pyr=3,5-dimethylpyrazolyl) were prepared from a P 1 source, R 2PH. In a one-pot reaction, eight P-P bonds are formed via a unique combination of substitution and base-induced reductive P-P coupling. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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