Strukturen, ionische Leitfähigkeit und atomare Diffusion in Perovskiten
Zusammenfassung der Projektergebnisse
The diffusion of oxygen defects in perovskite related compounds has been studied by electrical conductivity including relaxation experiments and by QENS in order to gain a deeper insight into the diffusion mechanisms. This work was further flanked by structural investigations by powder diffraction and by Mössbauer spectroscopy to access local environments. The investigation has been successful in identifying microscopic diffusion modes. However these must be attributed to local diffusion processes, while they can not be related directly to the macroscopic mass transport as evident e. g. from the different activation energies involved. Thus the nature of the oxygen conduction mechanism in perovskite-like compounds remains under discussion including an intense debate on the relevance of a possible dynamic coupling between rotational and translational motions of oxygen ions. It is expected at this time that a significant progress including a unique interpretation of the diffusion process on an atomic scale would become possible if the present study on powder materials could be extended to single crystals. However such material is not available at the present time. In electrical conductivity the ever asked question of the influence of grain boundaries would be overcome and the anisotropy of macroscopic transport becomes accessible. Single crystals would also provide quite a new quality of data in QENS. hi particular, the intensity of the signal would become more favourable for the interesting Q-directions and the data evaluation would allow for much stronger statements when the draw back from powder averaging is avoided.
Projektbezogene Publikationen (Auswahl)
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E.Mashkina, C.McCammon, F.Seifert, "A Mössbauer study of oxygen vacancy and cation distribution in 6H-BaTi1-xFexO3-x/2, J. Solid State Chemistry 177 (2004), 262-267
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E. Mashkina, M.Baier, A.Magerl, M.Göbbels, F.Seifert, "Resistivity relaxation, a new approach to study ionic mobility in perovskite mixed conductors like CaTi0,7yFe0,3O3-δ, Ionics 11 (2005), 269-274
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E. Mashkina, L.A.Dunyushkina, A.K.Demin, M. Goebbels, R.Hock, A.Magerl. Proceeding of Fifth European Solid Oxide Fuel Cell Forum, July 2002, Lucerne, Switzerland. Vol.2. P.695-699
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E. Mashkina, M.Baier, M.Göbbels, F.Seifert, A.Magerl, 3rd European Conference on Neutron Scattering, September 3-6, 2003, Montpellier, France
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E. Mashkina, M.Baier, M.Göbbels, F.Seifert, A.Magerl, Deutsche Gesellschaft für Kristallographie (DGK), Deutsche Gesellschaft für Kristallwachstum und Kristallzüchtung (DGKK) und Nationalkomitee für Kristallographie der Österreichischen Akademie der Wissenschaften (NKK-ÖAW), 28 Februar- 4 März, 2005, Köln, Germany
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E. Mashkina, M.Göbbels, F.Seifert, A.Magerl, J. Ollivier, JCNS Symposium and EU User Meeting, 16-17 February, 2006, Jülich, Germany
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E. Mashkina, M.Göbbels, F.Seifert, A.Magerl, Rennes-Erlangen Symposium of Chemestry, June 20-23, 2006; Reimes; France
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E. Mashkina, M.Göbbels, F.Seifert, A.Magerl, The 6th International Conference on Quasielastic Neutron scattering, September 4-7, 2002, Potsdam, Germany
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L.A. Dunyushkina, E.Mashkina, I.Yu. Nechaev, A.A.Babkina, N.O. Esina, B.V.Zhuravlev, A.K.Demin "Influence of Acceptor Doping on Ionic Conductivity in Alkali Earth Titanate Perovskites", Ionics. 8 (2002), 293-299
