Publication
Title
Ordering of tetrahedral chains in the $Sr_{2}MnGaO_{5}$ brownmillerite
Author
Abstract
 Tetrahedral chain ordering in the Sr2MnGaO5 structure is studied using electron diffraction (ED) and high-resolution electron microscopy. The ED patterns show the presence of satellite reflections, which indicate a commensurately modulated structure with a = 5.4056(8) Angstrom b 16.171(3) Angstrom, c = 5.5592(7) Angstrom, q - 1/2c*, superspace group Immma(00gamma,)s00. The Superstructure arises due to ordering of the two types of symmetry related tetrahedral chains (L and R) according to a ... LRLR ... sequence, where L and R chains alternate along the c-axis within the same (GaO) layer. Numerous defects at different structural levels were observed, comprising interleaving L and R chains, violation of the ... LRLR ... chain sequence within one layer, different stacking modes of the ... LRLR ... ordered layers with subsequent alternation of blocks of different width along the h-axis of the brownmillerite subcell and island fragmentation of the modulated superstructure. By in situ heating ED experiments it is found that the long-range ordering of the tetrahedral chains is stable tip to 665degreesC and is completely suppressed at 905degreesC. (C) 2003 Elsevier Inc. All rights reserved.
Language
English
Source (journal)
Journal of solid state chemistry. - London
Publication
London : 2003
ISSN
0022-4596
Volume/pages
174:2(2003), p. 319-328
ISI
000185180500011
Full text (Publisher's DOI)
Full text (publisher's version - intranet only)
UAntwerpen
 Faculty/Department Research group Publication type Subject Affiliation Publications with a UAntwerp address