Local structural properties of (Mn,Fe) Nb2O6 from Mossbauer and X-ray absorption spectroscopy.

Tarantino, S. C. and Ghigna, P. and McCammon, C. and Amantea, R. and Carpenter, M. A. (2005) Local structural properties of (Mn,Fe) Nb2O6 from Mossbauer and X-ray absorption spectroscopy. Acta Crystallographica Section B - Structural Science, 61. pp. 250-257. DOI 10.1107/S0108768105008116

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Abstract

The MnNb2O6–FeNb2O6 solid solution has been investigated by Fe–K- and Mn–K-edge X-ray absorption (XANES and EXAFS), and Mo¨ ssbauer spectroscopy. The first-shell M—O bond lengths deduced from EXAFS show a fairly small compositional dependence. A degree of static disorder, which increases with increasing manganese content, is clearly seen by the loss of correlation for the next-neighbour (NN) interaction. Hyperfine parameters from Mo¨ ssbauer spectra are consistent with variations in the average environment, as recorded by X-ray data. Line broadening of the Mo¨ ssbauer spectra provides evidence for next-neighbour effects and is consistent with there being no significant clustering of Fe or Mn within the samples. There appear to be differences in the way the columbite structure accommodates Fe2+ and Mn2+ ions. In ferrocolumbite all the Fe octahedra are close to being identical, while there are local structural heterogeneities at a longer length scale, presumably in ordering the precise topology of polyhedra immediately adjacent to the octahedron. By contrast, the manganocolumbite seems to have some diversity in the precise coordination at the MnO6 octahedra, but a greater uniformity in how the adjacent polyhedra are configured around them.

Item Type:	Article
Uncontrolled Keywords:	2005 AREP 2005 P IA48
Subjects:	03 - Mineral Sciences
Divisions:	03 - Mineral Sciences
Journal or Publication Title:	Acta Crystallographica Section B - Structural Science
Volume:	61
Page Range:	pp. 250-257
Identification Number:	10.1107/S0108768105008116
Depositing User:	Sarah Humbert
Date Deposited:	16 Aug 2010 13:32
Last Modified:	23 Jul 2013 09:59
URI:	http://eprints.esc.cam.ac.uk/id/eprint/1840

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