Structure and Failure Mechanism of the Thermoelectric CoSb_3/TiCoSb Interface
Guodong Li, Shiqiang Hao, Umut Aydemir, Max Wood, William A. Goddard III, Pengcheng Zhai, Qingjie Zhang, G. Jeffrey Snyder
Abstract
The brittle behavior and low strength of CoSb_3/TiCoSb interface are serious issues concerning the engineering applications of CoSb_3 based or CoSb_3/TiCoSb segmented thermoelectric devices. To illustrate the failure mechanism of the CoSb_3/TiCoSb interface, we apply density functional theory to investigate the interfacial behavior and examine the response during tensile deformations. We find that both CoSb_3(100)/TiCoSb(111) and CoSb_3(100)/TiCoSb(110) are energetically favorable interfacial structures. Failure of the CoSb_3/TiCoSb interface occurs in CoSb_3 since the structural stiffness of CoSb_3 is much weaker than that of TiCoSb. This failure within CoSb_3 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 the CoSb_3/TiCoSb interface is similar to that of bulk CoSb_3, but the ideal tensile strength and failure strain of the CoSb_3/TiCoSb interface are much lower than those of bulk CoSb_3. This can be attributed to the weakened stiffness of the Co–Sb framework due to structural rearrangement near the interfacial region.
Group Members
Li, G., Hao, S., Aydemir, U., Wood, M., III, W. A. G., Zhai, P., Zhang, Q., & Snyder, G. J. (2016). Structure and Failure Mechanism of the Thermoelectric CoSb_3/TiCoSb Interface. *ACS Appl. Mater. Interfaces*, *8*(46), 31968-31977.