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Ab initio determination and Rietveld refinement of the crystal structure of Ba7Cl2F12

Published online by Cambridge University Press:  10 January 2013

B. Es-Sakhi
Affiliation:
Laboratoire d’Instrumentation et de Mesures (LIM), Département de Physique, Faculté des Sciences, Université Ibnou Zohr, 80000 Agadir, Maroc
P. Gravereau
Affiliation:
Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS), 87, Av. Schweitzer, 33608 Pessac Cedex, France
C. Fouassier
Affiliation:
Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS), 87, Av. Schweitzer, 33608 Pessac Cedex, France

Abstract

The structure of Ba7Cl2F12 has been determined ab initio from conventional X-ray powder diffraction data by the “heavy atom” method. The cell is hexagonal (space group P6¯, Z=1), with a=10.6373(2) Å and c=4.1724(2) Å. Refinement of 38 parameters by the Rietveld method, using 278 reflections, leads to cRwp=0.173, cRp=0.135, and RB=0.054. The structure has common characteristics with that of the other BaF2-rich fluorochloride, Ba12Cl5F19. In both phases Ba2+ ions lie in tricapped trigonal prisms formed by nine halide ions, and Cl ions occupy the center of trigonal prisms of Ba2+ ions. F ions are located in cationic tetrahedra or square pyramids.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1998

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