Acta Crystallographica Section A

Foundations of Crystallography

Volume 69, Part 6 (November 2013)


research papers



Acta Cryst. (2013). A69, 570-582    [ doi:10.1107/S0108767313024458 ]

Comparative study of X-ray charge-density data on CoSb3

M. S. Schmøkel, L. Bjerg, F. K. Larsen, J. Overgaard, S. Cenedese, M. Christensen, G. K. H. Madsen, C. Gatti, E. Nishibori, K. Sugimoto, M. Takata and B. B. Iversen

Abstract: CoSb3 is an example of a highly challenging case for experimental charge-density analysis due to the heavy elements (suitability factor of ~0.01), the perfect crystallinity and the high symmetry of the compound. It is part of a family of host-guest structures that are potential candidates for use as high-performance thermoelectric materials. Obtaining and analysing accurate charge densities of the undoped host structure potentially can improve the understanding of the thermoelectric properties of this family of materials. In a previous study, analysis of the electron density gave a picture of covalent Co-Sb and Sb-Sb interactions together with relatively low atomic charges based on state-of-the-art experimental and theoretical data. In the current study, several experimental X-ray diffraction data sets collected on the empty CoSb3 framework are compared in order to probe the experimental requirements for obtaining data of high enough quality for charge-density analysis even in the case of very unsuitable crystals. Furthermore, the quality of the experimental structure factors is tested by comparison with theoretical structure factors obtained from periodic DFT calculations. The results clearly show that, in the current study, the data collected on high-intensity, high-energy synchrotron sources and very small crystals are superior to data collected at conventional sources, and in fact necessary for a meaningful charge-density study, primarily due to greatly diminished effects of extinction and absorption which are difficult to correct for with sufficient accuracy.

Keywords: charge density; thermoelectric materials; synchrotron X-ray diffraction; low-temperature crystallography; quantum theory of atoms in molecules.


pdfdisplay filedownload file

Portable Document Format (PDF) file
[ doi:10.1107/S0108767313024458/pc5032sup1.pdf ]
Supplementary material


Notes:

To open or display or play some files, you may need to set your browser up to use the appropriate software. See the full list of file types for an explanation of the different file types and their related mime types and, where available links to sites from where the appropriate software may be obtained.

The download button will force most browsers to prompt for a file name to store the data on your hard disk.

Where possible, images are represented by thumbnails.

 bibliographic record in  format

  Find reference:   Volume   Page   
  Search:     From   to      Advanced search

Copyright © International Union of Crystallography
IUCr Webmaster