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Deformation mechanisms in high-efficiency thermoelectric layered Zintl compounds

Li, Guodong and Aydemir, Umut and Wood, Max and An, Qi and Goddard, William A., III and Zhai, Pengcheng and Zhang, Qingjie and Snyder, G. Jeffrey (2017) Deformation mechanisms in high-efficiency thermoelectric layered Zintl compounds. Journal of Materials Chemistry A (19). pp. 9050-9059. ISSN 2050-7488. doi:10.1039/c7ta02080e.

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Recent experiments have uncovered n-type Zintl compounds including layered Mg_3Sb_2 with high thermoelectric efficiency. However, until now the mechanics of Mg_3Sb_2, which is important to understand for its widespread applications, has not been investigated. Here, we used density functional theory (DFT) to determine the deformation and failure mechanism of Mg_3Sb_2, and compared with isostructural CaMg_2Sb_2 and CaZn_2Sb_2 crystals. Mg_3Sb_2 is found to have a very low ideal shear strength of 1.95 GPa. The weakly ionic Mg–Sb bond, which links the Mg^(2+) sheet structure and the [Mg_2Sb_2]^(2−) substructure, breaks and creates pathways to slip between different [Mg_2Sb_2]^(2−) substructures under pure shear deformation in Mg_3Sb_2. The substitution of the Mg^(2+) sheet structure by a more electropositive Ca^(2+) leads to a much higher ideal shear strength of 4.07 GPa in isostructural CaMg_2Sb_2 compared with that in Mg_3Sb_2. The substitution of the [Mg_2Sb_2]^(2−) substructure by [Zn_2Sb_2]^(2−) in CaMg_2Sb_2 has little influence on the mechanical strength, leading to similar ideal shear strength for the CaZn_2Sb_2 and CaMg_2Sb_2. To enhance the mechanical strength of Mg_3Sb_2, we suggest that the weakly ionic Mg–Sb bond should be strengthened to improve the interaction between the Mg2+ sheet structure and the [Mg_2Sb_2]^(2−) substructure by appropriate doping strategies such as the partial substitution of Mg by more electropositive cations of Ca or Sr. These deformation modes are essential to understand the intrinsic mechanical process of this novel class of thermoelectric materials, which provides insightful guidance for designing high-performance layered Zintl compounds with improved strength and ductility.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Li, Guodong0000-0002-4761-6991
Aydemir, Umut0000-0003-1164-1973
Wood, Max0000-0003-2758-6155
An, Qi0000-0003-4838-6232
Goddard, William A., III0000-0003-0097-5716
Zhai, Pengcheng0000-0002-5737-5220
Snyder, G. Jeffrey0000-0003-1414-8682
Additional Information:© 2017 The Royal Society of Chemistry. Received 7th March 2017; Accepted 4th April 2017; First published on 04 Apr 2017. This work is partially supported by the National Basic Research Program of China (973-program) under Project no. 2013CB632505, the 111 Project of China under Project no. B07040, Materials Project by the Department of Energy Basic Energy Sciences Program under Grant No. EDCBEE, DOE Contract DE-AC02-05CH11231, and China Postdoctoral Science Foundation (408-32200031). We would like to acknowledge the Jet Propulsion Laboratory, California Institute of Technology, as a funding source under a contract with the National Aeronautics and Space Administration, which was supported by the NASA Science Missions Directorate's Radioisotope Power Systems Technology Advancement Program. Q. A. was supported by U. S. Nuclear Regulatory Commission (NRC) under Cooperative Agreement Number NRC-HQ-84-15-G-0028.
Funding AgencyGrant Number
National Basic Research Program of China2013CB632505
111 Project of ChinaB07040
Department of Energy (DOE)DE-AC02-05CH11231
China Postdoctoral Science Foundation408-32200031
Nuclear Regulatory CommissionNRC-HQ-84-15-G-0028
Issue or Number:19
Record Number:CaltechAUTHORS:20170426-085318914
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Official Citation:Deformation mechanisms in high-efficiency thermoelectric layered Zintl compounds Guodong Li, Umut Aydemir, Max Wood, Qi An, William A. Goddard III, Pengcheng Zhai, Qingjie Zhang and G. Jeffrey Snyder J. Mater. Chem. A, 2017, 5, 9050-9059 DOI: 10.1039/C7TA02080E
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76940
Deposited By: Tony Diaz
Deposited On:26 Apr 2017 16:29
Last Modified:15 Nov 2021 17:04

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