Nanotwin-induced ductile mechanism in thermoelectric semiconductor PbTe

Creators: Huang, Min; Zhai, Pengcheng; Li, Guodong; An, Qi; Morozov, Sergey I.; Li, Wenjuan; Zhang, Qingjie; Goddard, William A., III

Abstract

Coherent twin boundaries (CTBs) with the lowest interfacial energy provide a strong phonon-CTB scattering source to suppress the lattice thermal conductivity needed for thermoelectric properties, but the impact on mechanical properties of PbTe remains unexplored. We construct nanotwinned structures with Pb- or Te-terminated CTB (Pb- or Te-CTB) along (111) plane and employ molecular dynamics simulations to examine structural evolution. We find that Pb-CTBs weaken ionic Pb-Te bonds to generate an easy dislocation source at CTBs. Due to nucleation and motion of partial dislocations on each Pb-CTB plane driven by shear load, Pb-CTBs gradually migrate to Te-CTBs, which is accompanied by breaking and re-forming of Pb-Te bonds. This "catching bond" maintains structural integrity while dramatically enhancing deformability of nanotwinned PbTe. Dislocations move from Te-CTBs toward twin lamellae, resulting in the structural slippage and fracture. These findings provide a theoretical strategy to improve the ductility of PbTe-based semiconductors through TB engineering.

Additional Information

© 2022 Elsevier. Received 14 September 2021, Revised 21 February 2022, Accepted 14 March 2022, Available online 6 April 2022. This work was supported by the National Natural Science Foundation of China (no. 52022074, 92163119, and 92163212) and the Fundamental Research Funds for the Central Universities (no. 2020-YB-039). W.A.G. thanks NSF (CBET-2005250) for support. S.I.M. is thankful for the support by Act 211 Government of the Russian Federation, under no. 02.A03.21.0011, and by the Supercomputer Simulation Laboratory of South Ural State University. We acknowledge Sandia National Laboratories for distributing the open-source MD software LAMMPS. Author contributions. Conceptualization, M.H., G.L., and P.Z.; methodology, M.H., G.L., and P.Z.; writing – original draft, M.H.; writing – review & editing, M.H., G.L., Q.A., and W.A.G.; validation, M.H. and W.L.; supervision, G.L., P.Z., and Q.Z.; funding acquisition, M.H., G.L., S.I.M., P.Z., and W.A.G.; resources, G.L., S.I.M., and Q.Z.; visualization, M.H. and W.L. The authors declare no competing interests. Data and code availability: Data supporting the findings of this paper are available within the article and its supplemental information files. Any additional information required to reanalyze the data reported in this paper is available from the lead contact upon request.

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