The crystal and magnetic structures of La 0.8Sr 0.2Fe 1-xCu xO 3-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 LaFeO 3, 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)O 6 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 μ x=2.66(3)μ B and 2.43(3)μ 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

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

NATALI SORA, Isabella;CARONNA, Tullio Giuseppe Maria;FONTANA, Francesca;
2012-01-01

Abstract

The crystal and magnetic structures of La 0.8Sr 0.2Fe 1-xCu xO 3-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 LaFeO 3, 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)O 6 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 μ x=2.66(3)μ B and 2.43(3)μ 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
journal article - articolo
2012
NATALI SORA, Isabella; Caronna, Tullio Giuseppe Maria; Fontana, Francesca; DE JULIÁN FERNÁNDEZ, Cesar; Caneschi, Andrea; Green, MARK A.
File allegato/i alla scheda:
File Dimensione del file Formato  
12_JSSC_Natali Sora.pdf

Solo gestori di archivio

Descrizione: publisher's version - versione dell'editore
Dimensione del file 763.55 kB
Formato Adobe PDF
763.55 kB Adobe PDF   Visualizza/Apri
12_JSSC_Natali Sora_supplementary mat.pdf

Solo gestori di archivio

Descrizione: publisher's version - versione dell'editore
Dimensione del file 80 kB
Formato Adobe PDF
80 kB Adobe PDF   Visualizza/Apri
Pubblicazioni consigliate

Aisberg ©2008 Servizi bibliotecari, Università degli studi di Bergamo | Terms of use/Condizioni di utilizzo

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10446/27854
Citazioni
  • Scopus 56
  • ???jsp.display-item.citation.isi??? 53
social impact