Roudebush, John H. and Toberer, Eric S. and Hope, Håkon and Snyder, G. Jeffrey and Kauzlarich, Susan M. (2011) Crystal Structure, Characterization and Thermoelectric Properties of the Type-I Clathrate Ba_(8-y)Sr_yAl_(14)Si_(32) (0.6 ≤ y ≤ 1.3) Prepared by Aluminum Flux. Journal of Solid State Chemistry, 184 (5). pp. 1176-1185. ISSN 0022-4596. https://resolver.caltech.edu/CaltechAUTHORS:20110608-081329151
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Abstract
The title compound was prepared as single crystals using an aluminum flux technique. Single crystal and powder X-ray diffraction indicate that this composition crystallizes in the clathrate type-I structure, space group Pm3̄n. Electron microprobe characterization indicates the composition to be Ba_(8−y)Sr_yAl_(14.2(2))Si_(31.8(2)) (0.77<y<1.3). Single-crystal X-ray diffraction data (90 and 12 K) were refined with the Al content fixed at the microprobe value (12 K data: R_1=0.0233, wR_2=0.0441) on a crystal of compositions Ba. The Sr atom preferentially occupies the 2a position; mixed Al/Si occupancy was found on all framework sites. These refinements are consistent with a fully occupied framework and nearly fully occupied cation guest sites as found by microprobe analysis. Temperature dependent electrical resistivity and thermal conductivity have been measured from room temperature to 1200 K on a hot-pressed pellet. Electrical resistivity reveals metallic behavior. The negative Seebeck coefficient indicates transport processes dominated by electrons as carriers. Thermal conductivity is between 22 and 25 mW/cm K. The sample shows n-type conductivity with a maximum figure of merit, zT of 0.3 at 1200 K. A single parabolic band model predicts a five-fold increase in zT at 800 K if carrier concentration is lowered.
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| Additional Information: | © 2011 Elsevier Inc. Received 11 December 2010; revised 18 February 2011; accepted 27 February 2011. Available online 8 March 2011. We gratefully acknowledge the financial support from NSF DMR0600742 and NASA Jet Propulsion Laboratory. We thank Cathie Condron for her early contributions to the research. | |||||||||
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| Subject Keywords: | Thermoelectric properties; Zintl phase; Low temperature X-ray diffraction; 12 K structure; Inorganic clathrate; Ba8Al16Si30; Clathrate type-I | |||||||||
| Issue or Number: | 5 | |||||||||
| Record Number: | CaltechAUTHORS:20110608-081329151 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20110608-081329151 | |||||||||
| Official Citation: | John H. Roudebush, Eric S. Toberer, Hakon Hope, G. Jeffrey Snyder, Susan M. Kauzlarich, Crystal structure, characterization and thermoelectric properties of the type-I clathrate Ba8-ySryAl14Si32 (0.6<=y<=1.3) prepared by aluminum flux, Journal of Solid State Chemistry, Volume 184, Issue 5, May 2011, Pages 1176-1185, ISSN 0022-4596, DOI: 10.1016/j.jssc.2011.02.027. (http://www.sciencedirect.com/science/article/pii/S0022459611000958) | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 23939 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Ruth Sustaita | |||||||||
| Deposited On: | 08 Jun 2011 18:05 | |||||||||
| Last Modified: | 03 Oct 2019 02:51 |
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