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The crystal structure of Ca7Zr7Ta6O36 refined using synchrotron-radiation data
1Research School of Chemistry, Australian National University, GPO Box 414, Canberra, ACT 2601, Australia. schmid@rsc.anu.edu.au
Acta Crystallographica. Section B, Structural Science
|August 6, 2000
Summary
The crystal structure of heptacalcium hexatantalum heptazirconium hexatriacontaoxide (Ca(7)Zr(7)Ta(6)O(36)) was determined using single-crystal X-ray diffraction. Its metal-atom ordering is partially disordered, similar to pyrochlores.
Area of Science:
- Crystallography
- Materials Science
- Inorganic Chemistry
Background:
- Understanding complex oxide structures is crucial for developing new materials.
- The pyrochlore structure type is a common framework for mixed metal oxides with interesting properties.
Purpose of the Study:
- To solve and refine the crystal structure of heptacalcium hexatantalum heptazirconium hexatriacontaoxide (Ca(7)Zr(7)Ta(6)O(36)).
- To investigate the metal-atom ordering within this complex oxide structure.
Main Methods:
- Single-crystal X-ray diffraction using synchrotron radiation.
- Structure solution by direct methods and refinement.
- Calculation of bond-valence sums to assess crystal chemistry.
Main Results:
- The crystal structure of Ca(7)Zr(7)Ta(6)O(36) was determined in space group Fddd.
- Cell dimensions: a = 36.394 (1), b = 7.3674 (5), c = 31.006 (2) Å.
- The refined metal-atom ordering scheme is partially disordered, resembling pyrochlore A/B ordering.
Conclusions:
- The crystal structure and partial metal-atom disorder of Ca(7)Zr(7)Ta(6)O(36) have been elucidated.
- Bond-valence sum calculations support the proposed crystal chemistry.
- The findings provide insights into the structural complexity of mixed metal oxides.
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