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Crystal structure of BaBi2Ta2O9

Published online by Cambridge University Press:  10 January 2013

Carlos O. Paiva-Santos ,
Talita Mazon ,
Maria A. Zaghete ,
André L. Campos ,
J. A. Varela  and
Cesar R. Foschini
Carlos O. Paiva-Santos
Affiliation:
Laboratório Computacional em Análises Cristalográficas e Cristalinas, LabCACC, Instituto de Química, UNESP, R. Prof. Francisco Degni s/n, 14800-900 Araraquara (SP), Brazil
Talita Mazon
Affiliation:
Laboratório Interdisciplinar em Cera⁁mica, LIEC, Instituto de Química, UNESP, R. Prof. Francisco Degni s/n, 14800-900 Araraquara (SP), Brazil
Maria A. Zaghete
Affiliation:
Laboratório Interdisciplinar em Cera⁁mica, LIEC, Instituto de Química, UNESP, R. Prof. Francisco Degni s/n, 14800-900 Araraquara (SP), Brazil
André L. Campos
Affiliation:
Laboratório Interdisciplinar em Cera⁁mica, LIEC, Instituto de Química, UNESP, R. Prof. Francisco Degni s/n, 14800-900 Araraquara (SP), Brazil
J. A. Varela
Affiliation:
Laboratório Interdisciplinar em Cera⁁mica, LIEC, Instituto de Química, UNESP, R. Prof. Francisco Degni s/n, 14800-900 Araraquara (SP), Brazil
Cesar R. Foschini
Affiliation:
Laboratório Interdisciplinar em Cera⁁mica, LIEC, Instituto de Química, UNESP, R. Prof. Francisco Degni s/n, 14800-900 Araraquara (SP), Brazil
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Abstract

The crystal structure of the Aurivillius compound Bi2BaTa2O9 prepared via the chemical route was determined by direct methods using EXPO97, and refined using the Rietveld method with conventional X-ray diffraction data. The structure was found to be tetragonal (space group I4/mmm, number 139) and Z=2, isomorphic of the Bi2BaNb2O9 reported by Blake and co-workers in the literature (1997). Two refinements were performed using the two asymmetry functions of DBWS-9807 (release 20/May/99). The unit cell for each case are: a=3.932 22(6) Å, c=25.5053(6) Å (RA) and a=3.932 50(7) Å, c=25.5069(6) Å (RCF). The differences for atom positions, interatomic distances and angles are in the range of one standard deviation. Final agreements factors are: Rwp=7.97%, S=1.84, RBragg=4.28%(RA), Rwp=7.98%, S=1.84, RBragg=4.30%(RCF). The occupancies of Ba and Bi in site 2b were refined but constrained to have their summation equal to 1.00. The same constraints were applied to the Ba and Bi of the 4e site. The results show that on site 2b there are 70% of Ba and 30% of Bi and on the site 4e there are 82% of Bi and 18% of Ba. The charge equilibrium is maintained for one standard deviation of the site occupancies.© 2000 International Centre for Diffraction Data.

Type
New Diffraction Data
Information
Powder Diffraction , Volume 15 , Issue 2 , June 2000 , pp. 134 - 138
Copyright
Copyright © Cambridge University Press 2000

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