Brittle Failure Mechanism in Thermoelectric Skutterudite CoSb_3
Abstract
Skutterudites based on CoSb_3 have high thermoelectric efficiency, but the low fracture strength is a serious consideration for commercial applications. To understand the origin of the brittleness in CoSb_3, we examine the response along various shear and tensile deformations using density functional theory. We find that the Co–Sb bond dominates the ideal strength. Among all the shear and tensile deformation paths, shearing along the (001)/⟨100⟩ slip system has the lowest ideal strength, indicating it is the most likely slip system to be activated under pressure. We also find that, because the Sb–Sb covalent bond is softer than the Co–Sb bond, the Sb-rings are less rigid than the Co–Sb frameworks, which leads to the Sb-rings softening before the Co–Sb frameworks. Further deformation leads to deconstruction of Sb-rings and collapse of Co–Sb frameworks, resulting in structural failure. Moreover, we find that filling of the CoSb_3 void spaces with such typical fillers as Na, Ba, or Yb has little effect on the ideal strength and failure mode, which can be understood because they have little effect on the Sb-rings.
Additional Information
© 2015 American Chemical Society. Received: June 15, 2015; Revised: September 3, 2015; Published: September 4, 2015. This work is partially supported by National Basic Research Program of China (973-program) under Project No. 2013CB632505, the 111 Project of China under Project No. B07040, Materials Project by Department of Energy Basic Energy Sciences Program under Grant No. EDCBEE, DOE Contract DE-AC02-05CH11231, National Natural Science Foundation of China (No. 11302156), and China Postdoctoral Science Foundation (408-32200031). Q.A. and W.A.G. were supported by the Defense Advanced Research Projects Agency (W31P4Q-13-1-0010, program manager, Judah Goldwasser).Attached Files
Supplemental Material - cm5b02268_si_001.pdf
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Additional details
- Eprint ID
- 61514
- Resolver ID
- CaltechAUTHORS:20151023-155156156
- 2013CB632505
- National Basic Research Program of China
- B07040
- 111 Project of China
- DE-AC02-05CH11231
- Department of Energy (DOE)
- 11302156
- National Natural Science Foundation of China
- 408-32200031
- China Postdoctoral Science Foundation
- W31P4Q-13-1-0010
- Defense Advanced Research Projects Agency (DARPA)
- Created
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2015-10-26Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field