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Titolo:
Anion rotation and cation transport in the rotor phase alpha-sodium orthophosphate: Paddle-wheel mechanism redefined in view of new experimental results
Autore:
Witschas, M; Eckert, H; Wilmer, D; Banhatti, RD; Funke, K; Fitter, J; Lechner, RE; Korus, G; Jansen, M;
Indirizzi:
Univ Munster, Inst Chem Phys, D-48149 Munster, Germany Univ Munster Munster Germany D-48149 Chem Phys, D-48149 Munster, Germany Univ Munster, Sonderforsch Bereich 458, D-48149 Munster, Germany Univ Munster Munster Germany D-48149 reich 458, D-48149 Munster, Germany Hahn Meitner Inst Kernforsch Berlin GmbH, D-14109 Berlin, Germany Hahn Meitner Inst Kernforsch Berlin GmbH Berlin Germany D-14109 Germany Max Planck Inst Festkorperforsch, D-70569 Stuttgart, Germany Max Planck Inst Festkorperforsch Stuttgart Germany D-70569 gart, Germany
Titolo Testata:
ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS
, volume: 214, anno: 2000,
parte:, 5
pagine: 643 - 673
SICI:
0942-9352(2000)214:<643:ARACTI>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
QUASI-ELASTIC SCATTERING; NEUTRON-SCATTERING; PERCOLATION MODEL; ION-TRANSPORT; TEMPERATURE; CONDUCTIVITY; CRYSTALS; DYNAMICS; NMR; REORIENTATIONS;
Keywords:
fast-ion conduction; rotor phases; paddle-wheel mechanism;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Eckert, H Univ Munster, Inst Chem Phys, Schlosspl 4-7, D-48149 Munster, Germany Univ Munster Schlosspl 4-7 Munster Germany D-48149 ter, Germany
Citazione:
M. Witschas et al., "Anion rotation and cation transport in the rotor phase alpha-sodium orthophosphate: Paddle-wheel mechanism redefined in view of new experimental results", Z PHYS CHEM, 214, 2000, pp. 643-673

Abstract

The high-temperature phase of sodium ortho-phosphate, alpha-Na3PO4, is characterized by a dynamic rotational disorder of its polyatomic anions and, at the same time, by a considerable translational mobility of its cations. During the past decade, there has been considerable controversy about the question of whether both kinds of motion are dynamically coupled. To resolve this issue we have probed anionic and cationic motion individually over a wide range of experimental time scales. Coherent quasielastic neutron scattering as well as temperature-dependent O-17 NMR lineshape and relaxation spectroscopy serve to characterize the rotational motion of the anions, whereas the cation motion is probed by high-frequency conductivity and Na-23 NMR relaxation measurements. On the picosecond timescale, the combined interpretation of the neutron scattering and electrical conductivity data suggests strong dynamic coupling between the rotation of the phosphate groups about one of the four threefold P-O axes and the spatial fluctuations of nearby sodium ions. On more extended timescales, the NMR data indicate an additional, slower process, corresponding to dynamic jump reorientations of the C-3 axis of rotation. This process appears to be coupled to the translational Na+ transport dynamics as suggested by a strong correspondence between the O-17 and Na-23 NMR relaxation characteristics and the electrical conductivities in the de plateau region. The Na+ transport process can be viewed as highly correlated, not unlike the chain mechanism observed in AgBr.

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Documento generato il 19/09/20 alle ore 09:19:32