Acta Crystallographica Section B

Structural Science

Volume 65, Part 3 (June 2009)

research papers

Acta Cryst. (2009). B65, 308-317 [ doi:10.1107/S0108768109014001 ]

Large, larger, largest - a family of cluster-based tantalum copper aluminides with giant unit cells. I. Structure solution and refinement

T. Weber, J. Dshemuchadse, M. Kobas, M. Conrad, B. Harbrecht and W. Steurer

Abstract: This is the first of two parts, where we report the structure determination of a novel family of cluster-based intermetallic phases of unprecedented complexity: cF444-Al_63.6Ta_36.4 (AT-19), a = 19.1663 (1) Å, V = 7040 Å³, cF(5928 - x)-Al_56.6Cu_3.9Ta_39.5, x = 20 (ACT-45), a = 45.376 (1) Å, V = 93 428 Å³ and cF(23 256 - x)-Al_55.4Cu_5.4Ta_39.1, x = 122 (ACT-71), a = 71.490 (4) Å, V = 365 372 Å³. The space group is $F{\bar 4}3m$ in all three cases. These cluster-based structures are closely related to the class of Frank-Kasper phases. It is remarkable that all three structures show the same average structure that resembles the cubic Laves phase.

Keywords: intermetallics; clusters; average structure; X-ray structure analysis.


	Structure factor file (CIF format) (56.7 kbytes) [ doi:10.1107/S0108768109014001/sn5082at19sup2.hkl ] Contains datablock at19

	Structure factor file (CIF format) (588.9 kbytes) [ doi:10.1107/S0108768109014001/sn5082act45sup3.hkl ] Contains datablock act45

	Structure factor file (CIF format) (2347.4 kbytes) [ doi:10.1107/S0108768109014001/sn5082act71sup4.hkl ] Contains datablock act71

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