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EFFECT OF LANTHANUM MANGANITE MODIFICATION BY CALCIUM AND/OR FLUORINE ON THE BONDING STRENGTH, MOBILITY AND REACTIVITY OF THE LATTICE AND SURFACE OXYGEN

Published online by Cambridge University Press:  11 February 2011

V. A. Sadykov
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su Novosibirsk State University, Novosibirsk, 630090, Russia.
T. G. Kuznetsova
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
A. V. Simakov
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
V. A. Rogov
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
V. I. Zaikovskii
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
E. M. Moroz
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
D. I. Kochubei
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
B. N. Novgorodov
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
V. P. Ivanov
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
S. N. Trukhan
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
G. S. Litvak
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
N. N. Bulgakov
Affiliation:
-Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia; sadykov@catalysis.nsk.su
V. V. Lunin
Affiliation:
Lomonosov Moscow State University, Moscow, Russia
E. Kemnitz
Affiliation:
-Institute for Chemistry, Humboldt- University, Berlin, Germany
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Abstract

Ca and/or F-modified samples of LaMnO3 have been prepared by the Pechini method. The bulk structure of samples was characterized by TEM, EXAFS and XRD, while the surface composition was studied by SIMS. Thermal analysis, O2 TPD, H2 TPR and isothermal pulse/flow samples reduction by CO were applied to characterize the accessible surface/bulk oxygen mobility and reactivity. A reasonable description of the experimental energetic spectrum of the surface oxygen for various types of regular and defect surface sites on the perovskite faces was achieved by using semiempirical Interacting Bonds Method in the slab approximation with a due regard for the surface face termination and relaxation. Fluorine was found to decrease the surface coverage by reactive weakly bound oxygen forms while increasing the bulk oxygen excess and mobility. Calcium generated reactive weakly bound oxygen forms while decreasing the oxygen excess in the lattice and converting the regular M-O oxygen forms into the bridging ones through migration to the surface.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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