TY - JOUR
T1 - Understanding the Intrinsic P-Type Behavior and Phase Stability of Thermoelectric α-Mg3Sb2
AU - Chong, Xiaoyu
AU - Guan, Pin Wen
AU - Wang, Yi
AU - Shang, Shun Li
AU - Paz Soldan Palma, Jorge
AU - Drymiotis, Fivos
AU - Ravi, Vilupanur A.
AU - Star, Kurt E.
AU - Fleurial, Jean Pierre
AU - Liu, Zi Kui
N1 - Funding Information:
This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and The Pennsylvania State University, under a contract with the National Aeronautics and Space Administration. The authors are thankful for the Scholarship from the China Scholarship Council (201608530171). First-principles calculations were carried out partially on the LION clusters at The Pennsylvania State University, partially on the resources of NERSC supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231, and partially on the resources of XSEDE supported by NSF with Grant ACI-1053575. This research received funding from the Pennsylvania State University’s Institute for CyberScience through the ICS Seed Grant Program (Chong, Wang, and Liu).
Publisher Copyright:
© Copyright 2018 American Chemical Society.
PY - 2018/11/26
Y1 - 2018/11/26
N2 - α-Mg3Sb2 is an excellent thermoelectric material through excess-Mg addition and n-type impurity doping to overcome its persistent p-type behavior. It is generally believed that the role of excess-Mg is to compensate the single Mg vacancy to realize n-type carrier conduction. In contrary to this belief, the present work indicates that the role of excess-Mg is to compensate the electronic charge of defect complex (VMg(2) + MgI)1-. The Mg solubility in α-Mg3+xSb2 is quite small when only considering a single defect, but it enlarged up to x = 0.011 with the defect complex (VMg(2) + MgI)1-, which is more reasonable as supported by experiments. Under Mg-poor conditions, VMg(1)2- and VMg(2)2- are the dominant defects, and their concentrations can reach (1.05-1.18) × 1019 cm-3 at 1200 K. Under Mg-rich conditions, (VMg(2) + MgI)1- is found to be the dominant reason for strong p-type behavior, and their concentrations can reach as high as 3.5 × 1020 cm-3, which shifts the Fermi level closer to the valence band maximum. The predicted carrier concentrations in the range 1017-1020 cm-3 are in the same range found experimentally for pure p-type α-Mg3Sb2.
AB - α-Mg3Sb2 is an excellent thermoelectric material through excess-Mg addition and n-type impurity doping to overcome its persistent p-type behavior. It is generally believed that the role of excess-Mg is to compensate the single Mg vacancy to realize n-type carrier conduction. In contrary to this belief, the present work indicates that the role of excess-Mg is to compensate the electronic charge of defect complex (VMg(2) + MgI)1-. The Mg solubility in α-Mg3+xSb2 is quite small when only considering a single defect, but it enlarged up to x = 0.011 with the defect complex (VMg(2) + MgI)1-, which is more reasonable as supported by experiments. Under Mg-poor conditions, VMg(1)2- and VMg(2)2- are the dominant defects, and their concentrations can reach (1.05-1.18) × 1019 cm-3 at 1200 K. Under Mg-rich conditions, (VMg(2) + MgI)1- is found to be the dominant reason for strong p-type behavior, and their concentrations can reach as high as 3.5 × 1020 cm-3, which shifts the Fermi level closer to the valence band maximum. The predicted carrier concentrations in the range 1017-1020 cm-3 are in the same range found experimentally for pure p-type α-Mg3Sb2.
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U2 - 10.1021/acsaem.8b01520
DO - 10.1021/acsaem.8b01520
M3 - Article
AN - SCOPUS:85060638372
VL - 1
SP - 6600
EP - 6608
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
SN - 2574-0962
IS - 11
ER -