Crystal structures and magnetic properties of strontium and copper doped lanthanum ferrites

Natali Sora, Isabella, Caronna, Tullio, Fontana, Francesca, de Julián Fernández, César, Caneschi, Andrea, Green, M.A. (2012) Crystal structures and magnetic properties of strontium and copper doped lanthanum ferrites. Journal of Solid State Chemistry, 191 . pp. 33-39. ISSN 0022-4596. (doi:10.1016/j.jssc.2012.02.020) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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http://doi.org/10.1016/j.jssc.2012.02.020

Abstract

The crystal and magnetic structures of La0.8Sr0.2Fe1?xCuxO3?w compounds, which exhibit coercive fields larger than any others reported for iron-based perovskites, have been analyzed at room temperature with the neutron powder diffraction technique and the Rietveld method of profile fitting. For x in the range 0.05–0.10 the material is monophasic with orthorhombic symmetry (space group Pnma), and crystallizes in the perovskite-like cell of LaFeO3, Fe/Cu cations occupy octahedral sites, La/Sr cations are twelve-fold coordinated. For x=0.20 the material is biphasic, with a main orthorhombic phase (space group Pnma) and a secondary rhombohedral phase with space group R-3c (hexagonal setting). The structural transition from the orthorhombic to the rhombohedral phase reduces the structural distortion of the (Fe/Cu)O6 octahedron. The average bond distance (Fe/Cu)–O and the pseudo-cubic unit cell volume decrease with increasing Cu content in accordance with the presence of higher valence states of the transition metals. The magnetic structure was modeled for the monophasic samples (x=0.05 and 0.10) assuming an antiferromagnetic interaction between Fe/Cu neighboring cations (G-type): the magnetic moments order antiferromagnetically along the b-axis, with the spin direction along a-axis. The magnetic moments of the Fe/Cu atoms are ?x=2.66(3)?B and 2.43(3)?B for the compositions x=0.05 and 0.10, respectively. By measuring the first magnetization curve and the hysteresis loops, coexisting antiferromagnetic and weak ferromagnetic interactions were observed for all samples.

Item Type: Article
DOI/Identification number: 10.1016/j.jssc.2012.02.020
Uncontrolled keywords: Lanthanum ferrites; Perovskite oxides; Neutron powder diffraction; Weak ferromagnetic interactions
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QD Chemistry > QD478 Solid State Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences
Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Mark Green
Date Deposited: 19 Oct 2015 13:55 UTC
Last Modified: 29 May 2019 16:10 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/51078 (The current URI for this page, for reference purposes)
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