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. 2018 Jan 15;8(1):797.
doi: 10.1038/s41598-017-19045-8.

Evidence of a cubic iron sub-lattice in t-CuFe2O4 demonstrated by X-ray Absorption Fine Structure

Francesco Caddeo  1   2 , Danilo Loche  1 , Maria F Casula  3 , Anna Corrias  4
Affiliations

Evidence of a cubic iron sub-lattice in t-CuFe2O4 demonstrated by X-ray Absorption Fine Structure

Francesco Caddeo et al. Sci Rep. .

Abstract

Copper ferrite, belonging to the wide and technologically relevant class of spinel ferrites, was grown in the form of t-CuFe2O4 nanocrystals within a porous matrix of silica in the form of either an aerogel or a xerogel, and compared to a bulk sample. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed the presence of two different sub-lattices within the crystal structure of t-CuFe2O4, one tetragonal and one cubic, defined by the Cu2+ and Fe3+ ions respectively. Our investigation provides evidence that the Jahn-Teller distortion, which occurs on the Cu2+ ions located in octahedral sites, does not affect the coordination geometry of the Fe3+ ions, regardless of their location in octahedral or tetrahedral sites.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Figure 1
Figure 1
XRD patterns of ACuFe, XCuFe and bulk-CuFe2O4. The pattern of the tetragonal and cubic phases of copper ferrite are also reported. *Represents a peak identified as a small impurity of CuO.
Figure 2
Figure 2
TEM images of the ACuFe (a,b) and XCuFe (c,d) nanocomposites; bright field on the left, dark field on the right.
Figure 3
Figure 3
FESEM images of the ACuFe (a), XCuFe (b) and bulk-CuFe2O4.
Figure 4
Figure 4
XANES spectra of ACuFe, XCuFe, and bulk-CuFe2O4, at the Fe and Cu K-edge. Bold line: samples; dots: γ-Fe2O3 in the case of Fe K-edge, CuO in the case of Cu K-edge. The pre-peak region is enlarged in the inset.
Figure 5
Figure 5
Fit of the EXAFS region at the Cu K-edge of the ACuFe, XCuFe and bulk-CuFe2O4 samples; k3χ(k) (left) and corresponding FTs (right). Full line: experiment; dots: fit.
Figure 6
Figure 6
Fit of the EXAFS region at the Fe K-edge of the ACuFe, XCuFe and bulk-CuFe2O4 samples; k3χ(k) (left) and corresponding FTs (right). Full line: experiment; dots: fit.
See this image and copyright information in PMC

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