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Published February 2009 | public
Journal Article

Structure and high-temperature thermoelectric properties of SrAl_2Si_2

Abstract

Single crystals of SrAl_2Si_2 were synthesized by reaction of the elements in an aluminum flux at 1000 °C. SrAl_2Si_2 is isostructural to CaAl2Si2 and crystallizes in the hexagonal space group P–3m1 (90 K, a=4.1834 (2), c=7.4104 (2) Å, Z=1, R1=0.0156, wR2=0.0308). Thermal analysis shows that the compound melts at 1020 °C. Low-temperature resistivity on single crystals along the c-axis shows metallic behavior with room temperature resistivity value of 7.5 mΩ cm. High-temperature Seebeck, resistivity, and thermal conductivity measurements were made on hot-pressed pellets. The Seebeck coefficient shows negative values in entire temperature range decreasing from −78 μV K^(−1) at room temperature to −34 μV K^(−1) at 1173 K. Seebeck coefficients are negative indicating n-type behavior; however, the temperature dependence is consistent with contribution from minority p-type carriers as well. The lattice contribution to the thermal conductivity is higher than for clathrate structures containing Al and Si, approximately 50 mW cm^(−1) K, and contributes to the overall low zT for this compound.

Additional Information

Copyright © 2008 Elsevier. Received 6 August 2008; revised 17 September 2008; accepted 20 September 2008. Available online 29 October 2008. The authors gratefully acknowledge Dr. Alexandra Navrotsky (Department of Chemistry and Thermochemistry Facility and NEAT ORU, University of California Davis) for use of the Scintag powder diffractometer. This work was supported by the National Science Foundation (Grant DMR-0600742), and CLC acknowledges a Tyco Electronics Foundation Fellowship in functional materials. Financial support for Caltech came from NASA-GRC NRA. Supporting information available Further details of the crystal structure investigation can be obtained from the Fachinformationszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany, (fax: (49) 7247-808-666; e-mail: crysdata@fiz.karlsruhe.de) on quoting the depository number CSD 419886.

Additional details

Created:
August 21, 2023
Modified:
October 18, 2023