Modeling and Rietveld-refinement of the crystal structure of Bi{sub 4}Ta{sub 2}O{sub 11} based on that of Bi{sub 7}Ta{sub 3}O{sub 18}

Journal Article · Fri Jan 01 04:00:00 EST 1999 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1998.7980· OSTI ID:329123

Ling, C D; Thompson, J G; Withers, R L; Schmid, S ^[1]

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1. Australian National Univ., Canberra (Australia). Research School of Chemistry

A P{bar 1} model for the crystal structure of Bi{sub 4}Ta{sub 2}O{sub 11} has been proposed based on units from the P1 crystal structure of Bi{sub 7}Ta{sub 3}O{sub 38}. The model was found to be plausible in terms of bond valence sums. When refined via the Rietveld method using X-ray (synchrotron) and neutron powder diffraction data, the final structure had greatly improved bond valence sums. The metal atom array approximates fluorite-type with regular step defects on (h k 0) planes (perpendicular to [111]{sub fluorite}). Regular TaO{sub 6} octahedra form corner-connected columns. Bismuth atoms are in high coordination environments similar to those found in fluorite-type. Bi{sub 7}Ta{sub 3}O{sub 18} and Bi{sub 4}Ta{sub 2}O{sub 11} are discussed in terms of their structural relationships to one another, to adjacent phases in the Bi{sub 2}O{sub 3}-Ta{sub 2}O{sub 5} system, and to structures proposed by earlier authors based on an archetypal fluorite-type substructure.

• OSTI ID: 329123
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 142; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BISMUTH OXIDES
CHEMICAL COMPOSITION
CRYSTAL MODELS
CRYSTAL STRUCTURE
NEUTRON DIFFRACTION
TANTALUM OXIDES
VALENCE
X-RAY DIFFRACTION