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The electron microscopy and XRD investigation of structure processes in CMR crystals LaMnO3+δ

Published online by Cambridge University Press:  01 February 2011

V.Sh. Shekhtman ,
V. Sedykh ,
N.S. Afonikova ,
A.V. Dubovitskii  and
V.I. Kulakov
V.Sh. Shekhtman
Affiliation:
Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432 RUSSIA E-mail: shekht@issp.ac.ru
V. Sedykh
Affiliation:
Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432 RUSSIA E-mail: shekht@issp.ac.ru
N.S. Afonikova
Affiliation:
Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432 RUSSIA E-mail: shekht@issp.ac.ru
A.V. Dubovitskii
Affiliation:
Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432 RUSSIA E-mail: shekht@issp.ac.ru
V.I. Kulakov
Affiliation:
Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432 RUSSIA E-mail: shekht@issp.ac.ru
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Abstract

The specific features of structural transformations in lanthanum manganite are analyzed in terms of the macrosymmetry conservation principle. The possible mechanisms of phase transformations are proposed reasoning from a sequence of structural transitions, including the restoration of a virtual configuration of cubic perovskite with double the lattice parameter. It has been synthesized and investigated three phases Pnma I, Pnma II, R3c. It has been shown by X-ray diffraction analysis and Mössbauer spectroscopy that the transition from the Pnma I to Pnma II phase in LaMnO3+d compound occurs through the intermediate phase Pnma II* virtually by “jump”. The HEED investigations of the synthesized phases have shown that the Pnma I and R3c phases have the expected simple pattern whereas the electron-diffraction pattern of the Pnma II phase strongly differs.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 839: Symposium P – Electron Microscopy of Molecular and Atom-Scale Mechanical Behavior, Chemistry, and Structure , 2004 , P3.5
Copyright
Copyright © Materials Research Society 2004

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References

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