Structure and Failure Mechanism of the Thermoelectric CoSb3/TiCoSb Interface

Guodong Li; Shiqiang Hao; Umut Aydemir; Max Wood; William A Goddard 3rd; Pengcheng Zhai; Qingjie Zhang; G Jeffrey Snyder

doi:10.1021/acsami.6b07320

Structure and Failure Mechanism of the Thermoelectric CoSb₃/TiCoSb Interface

ACS Appl Mater Interfaces. 2016 Nov 23;8(46):31968-31977. doi: 10.1021/acsami.6b07320. Epub 2016 Nov 9.

Authors

Guodong Li^{1

2}, Shiqiang Hao², Umut Aydemir², Max Wood², William A Goddard 3rd³, Pengcheng Zhai¹, Qingjie Zhang¹, G Jeffrey Snyder^{2

4}

Affiliations

¹ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology , Wuhan 430070, China.
² Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States.
³ Materials and Process Simulation Center, California Institute of Technology , Pasadena, California 91125, United States.
⁴ ITMO University , St. Petersburg, 197101 Russia.

PMID: 27801564
DOI: 10.1021/acsami.6b07320

Abstract

The brittle behavior and low strength of CoSb₃/TiCoSb interface are serious issues concerning the engineering applications of CoSb₃ based or CoSb₃/TiCoSb segmented thermoelectric devices. To illustrate the failure mechanism of the CoSb₃/TiCoSb interface, we apply density functional theory to investigate the interfacial behavior and examine the response during tensile deformations. We find that both CoSb₃(100)/TiCoSb(111) and CoSb₃(100)/TiCoSb(110) are energetically favorable interfacial structures. Failure of the CoSb₃/TiCoSb interface occurs in CoSb₃ since the structural stiffness of CoSb₃ is much weaker than that of TiCoSb. This failure within CoSb₃ can be explained through the softening of the Sb-Sb bond along with the cleavage of the Co-Sb bond in the interface. The failure mechanism of the CoSb₃/TiCoSb interface is similar to that of bulk CoSb₃, but the ideal tensile strength and failure strain of the CoSb₃/TiCoSb interface are much lower than those of bulk CoSb₃. This can be attributed to the weakened stiffness of the Co-Sb framework because of structural rearrangement near the interfacial region.

Keywords: bond breakage; ideal strength; interfacial structure; tensile failure mode; thermoelectric.