Synthesis, crystal and magnetic structure of a novel brownmillerite-type compound Ca2Co1.6Ga0.4O5статья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The novel compound Ca2Co1.6Ga0.405 with brownmillerite (BM) structure has been prepared from citrates at 950degreesC. The crystal structure of Ca2Co1.6Ga0.405 was refined, from neutron powder diffraction (NPD) data, in space group Pnma, a = 5.3022(6) Angstrom, b = 14.884(2) Angstrom, c = 5.5276(6) Angstrom, chi(2) = 1.798, R-F(2) = 0.0455 R-wp = 0.0378 and R-p = 0.0292. On the basis of the NPD refinement the compound was found to be a G-type antiferromagnet (space group Pn'm'a) at room temperature, with the magnetic moments of cobalt atoms directed along chains of tetrahedra in the BM structure. Electron diffraction and electron microscopy studies revealed disorder in the crystallites. which can be interpreted as the presence of slabs with BM-type structure of Pnma and I2mb symmetry. (C) 2004 Elsevier Inc. All rights reserved.