Eur. Phys. J. B 21, 521-526 (2001)
https://doi.org/10.1007/PL00011125

Structural features of the La-Sr-Fe-Co-O system

¹ Department of Solid State Physics, Eötvös University, 1518 Budapest, POB 32, Hungary
² Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, 1525 Budapest, POB 49, Hungary
³ Research Group for Nuclear Methods in Structural Chemistry of the Hungarian Academy of Sciences, Department of Nuclear Chemistry, Eötvös University, 1518 Budapest, POB 32, Hungary
⁴ Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Calcutta 700032, India
⁵ Institut für Festkörper- und Werkstofforschung, Helmholtzstrasse 20, 01069 Dresden, Germany
⁶ Institut de Physique et Chimie des Matériaux de Strasbourg, UMR C75040 CNRS-ULP, 23 rue du Loess, 67037 Strasbourg, France

Corresponding author: ^a bakonyi@szfki.hu

Received: 22 January 2001
Published online: 15 June 2001

Abstract

A structural study has been performed on the La_0.8Sr_0.2Fe_xCoO₃ (x = 0.025 to 0.3) system displaying large magnetoresistance (MR) at room temperature. A detailed analysis of the crystal structure and microstructure was done by X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM). The atomic resolution TEM images and the appearing superreflections in the corresponding SAED patterns revealed that a superstructure is formed due to the presence of iron. The correlation between the ordered microstructure and the observed large MR ratio is discussed. ⁵⁷Fe Mössbauer spectroscopy was utilized to gain information on the valence state of iron in the sample with x = 0.3. The lattice parameters of Fe- doped La_0.8Sr_0.2Fe_xCoO₃ compounds were found to increase monotonously with increasing Fe content. The valence state of iron was found to be Fe³⁺.