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Title: EuBaFe{sub 2}O{sub 5}: Extent of charge ordering by Mossbauer spectroscopy and high-intensity high-resolution powder diffraction

Abstract

{sup 151}Eu and {sup 57}Fe Mossbauer spectroscopy, differential scanning calorimetry, and high-intensity high-resolution synchrotron powder diffraction were used to determine the extent of long- and short-range charge ordering below the first-order Verwey-type transition in EuBaFe{sub 2}O{sub 5}, the oxygen content of which was homogenized by annealing in sealed ampoule. The diffraction gives 0.68(5) valence unit of charge separation at 100K. Interpretation of this value as 68% of iron being long-range charge ordered correlates with the total transition entropy per formula of about 0.7 of the theoretical value 2Rln2 that would be valid for all iron atoms being fully charge ordered. For long- and short-range order combined, {sup 57}Fe Mossbauer spectroscopy suggests that about 90% of iron atoms occur as charge-ordered integer Fe{sup 2+} and Fe{sup 3+}. The residual 10% are the Fe{sup 2+} and Fe{sup 3+} that did not find the way to order. Local oxygen non-stoichiometry defects that revert the direction of the charge order are suggested as one of the origins of the short-range charge order. Accordingly, the long-range charge order seen by diffraction is highest in the portion of the sample that converts last upon heating, having the most ideal valence ratio.

Authors:
 [1];  [2];  [2]
  1. Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway), E-mail: pavel.karen@kjemi.uio.no
  2. Department of Physics, Abo Akademi, FI-20500 Turku (Finland)
Publication Date:
OSTI Identifier:
21015630
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2006.09.021; PII: S0022-4596(06)00522-6; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANNEALING; BARIUM COMPOUNDS; CALORIMETRY; DIFFRACTION; ENTROPY; EUROPIUM COMPOUNDS; IRON; IRON IONS; IRON OXIDES; MOESSBAUER EFFECT; PEROVSKITE; TEMPERATURE RANGE 0065-0273 K

Citation Formats

Karen, P., Gustafsson, K., and Linden, J.. EuBaFe{sub 2}O{sub 5}: Extent of charge ordering by Mossbauer spectroscopy and high-intensity high-resolution powder diffraction. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2006.09.021.
Karen, P., Gustafsson, K., & Linden, J.. EuBaFe{sub 2}O{sub 5}: Extent of charge ordering by Mossbauer spectroscopy and high-intensity high-resolution powder diffraction. United States. doi:10.1016/j.jssc.2006.09.021.
Karen, P., Gustafsson, K., and Linden, J.. Mon . "EuBaFe{sub 2}O{sub 5}: Extent of charge ordering by Mossbauer spectroscopy and high-intensity high-resolution powder diffraction". United States. doi:10.1016/j.jssc.2006.09.021.
@article{osti_21015630,
title = {EuBaFe{sub 2}O{sub 5}: Extent of charge ordering by Mossbauer spectroscopy and high-intensity high-resolution powder diffraction},
author = {Karen, P. and Gustafsson, K. and Linden, J.},
abstractNote = {{sup 151}Eu and {sup 57}Fe Mossbauer spectroscopy, differential scanning calorimetry, and high-intensity high-resolution synchrotron powder diffraction were used to determine the extent of long- and short-range charge ordering below the first-order Verwey-type transition in EuBaFe{sub 2}O{sub 5}, the oxygen content of which was homogenized by annealing in sealed ampoule. The diffraction gives 0.68(5) valence unit of charge separation at 100K. Interpretation of this value as 68% of iron being long-range charge ordered correlates with the total transition entropy per formula of about 0.7 of the theoretical value 2Rln2 that would be valid for all iron atoms being fully charge ordered. For long- and short-range order combined, {sup 57}Fe Mossbauer spectroscopy suggests that about 90% of iron atoms occur as charge-ordered integer Fe{sup 2+} and Fe{sup 3+}. The residual 10% are the Fe{sup 2+} and Fe{sup 3+} that did not find the way to order. Local oxygen non-stoichiometry defects that revert the direction of the charge order are suggested as one of the origins of the short-range charge order. Accordingly, the long-range charge order seen by diffraction is highest in the portion of the sample that converts last upon heating, having the most ideal valence ratio.},
doi = {10.1016/j.jssc.2006.09.021},
journal = {Journal of Solid State Chemistry},
number = 1,
volume = 180,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
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