Structural analysis of Sr8Ga16Ge30 clathrate compound

S. B. Schujman, G. S. Nolas, R. A. Young, C. Lind, A. P. Wilkinson, G. A. Slack, R. Patschke, Mercouri G Kanatzidis, M. Ulutagay, S. J. Hwu

Research output: Contribution to journalArticle

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Abstract

Crystal structural characterization of the Sr8Ga16Ge30 compound was carried out with the Rietveld refinement method using x-ray powder diffraction data. The structure corresponds to that of the type-I clathrate hydrate, with the Sr atoms filling the "cages" formed by the Ga and Ge atoms. Anisotropic displacement parameters were refined. The limiting figure for rms values of the Sr(1) atoms enclosed in the dodecahedral cages is a sphere, while that for the Sr(2) atoms in the tetrakaidecahedral cages move is an oblate ellipsoid. A comparison of the sizes of the cages in this structure with the ones in other M8GaxGe46-x (M=K, Ba, or void) structures shows that once the structure is filled (i) there is very little variation in size of the tetrakaidecahedral cages and (ii) the dodecahedral cages expand only slightly (measurably) as a function of the filler size. This is an important result from the thermoelectric point of view because it means that once the structure is full, the cages will not "close over" the guests, limiting their movement and, thus, raising the thermal conductivity. The melting point of Sr8Ga16Ge30 is approximately 765°C and the apparent optical gap is 0.05 eV.

Original languageEnglish
Pages (from-to)1529-1533
Number of pages5
JournalJournal of Applied Physics
Volume87
Issue number3
Publication statusPublished - Feb 2000

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clathrates
structural analysis
atoms
ellipsoids
fillers
hydrates
melting points
voids
thermal conductivity
diffraction
crystals
x rays

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physics and Astronomy (miscellaneous)

Cite this

Schujman, S. B., Nolas, G. S., Young, R. A., Lind, C., Wilkinson, A. P., Slack, G. A., ... Hwu, S. J. (2000). Structural analysis of Sr8Ga16Ge30 clathrate compound. Journal of Applied Physics, 87(3), 1529-1533.

Structural analysis of Sr8Ga16Ge30 clathrate compound. / Schujman, S. B.; Nolas, G. S.; Young, R. A.; Lind, C.; Wilkinson, A. P.; Slack, G. A.; Patschke, R.; Kanatzidis, Mercouri G; Ulutagay, M.; Hwu, S. J.

In: Journal of Applied Physics, Vol. 87, No. 3, 02.2000, p. 1529-1533.

Research output: Contribution to journalArticle

Schujman, SB, Nolas, GS, Young, RA, Lind, C, Wilkinson, AP, Slack, GA, Patschke, R, Kanatzidis, MG, Ulutagay, M & Hwu, SJ 2000, 'Structural analysis of Sr8Ga16Ge30 clathrate compound', Journal of Applied Physics, vol. 87, no. 3, pp. 1529-1533.
Schujman SB, Nolas GS, Young RA, Lind C, Wilkinson AP, Slack GA et al. Structural analysis of Sr8Ga16Ge30 clathrate compound. Journal of Applied Physics. 2000 Feb;87(3):1529-1533.
Schujman, S. B. ; Nolas, G. S. ; Young, R. A. ; Lind, C. ; Wilkinson, A. P. ; Slack, G. A. ; Patschke, R. ; Kanatzidis, Mercouri G ; Ulutagay, M. ; Hwu, S. J. / Structural analysis of Sr8Ga16Ge30 clathrate compound. In: Journal of Applied Physics. 2000 ; Vol. 87, No. 3. pp. 1529-1533.
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