Abstract
α-Mg 3 Sb 2 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 (V Mg(2) + Mg I ) 1- . The Mg solubility in α-Mg 3+x Sb 2 is quite small when only considering a single defect, but it enlarged up to x = 0.011 with the defect complex (V Mg(2) + Mg I ) 1- , which is more reasonable as supported by experiments. Under Mg-poor conditions, V Mg(1) 2- and V Mg(2) 2- are the dominant defects, and their concentrations can reach (1.05-1.18) × 10 19 cm -3 at 1200 K. Under Mg-rich conditions, (V Mg(2) + Mg I ) 1- is found to be the dominant reason for strong p-type behavior, and their concentrations can reach as high as 3.5 × 10 20 cm -3 , which shifts the Fermi level closer to the valence band maximum. The predicted carrier concentrations in the range 10 17 -10 20 cm -3 are in the same range found experimentally for pure p-type α-Mg 3 Sb 2 .
| Original language | English (US) |
|---|---|
| Pages (from-to) | 6600-6608 |
| Number of pages | 9 |
| Journal | ACS Applied Energy Materials |
| Volume | 1 |
| Issue number | 11 |
| DOIs | |
| State | Published - Nov 26 2018 |
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All Science Journal Classification (ASJC) codes
- Energy Engineering and Power Technology
- Chemical Engineering (miscellaneous)
- Electrochemistry
- Materials Chemistry
- Electrical and Electronic Engineering
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Understanding the Intrinsic P-Type Behavior and Phase Stability of Thermoelectric α-Mg 3 Sb 2 . / Chong, Xiaoyu; Guan, Pin Wen; Wang, Yi; Shang, Shunli; Paz Soldan Palma, Jorge; Drymiotis, Fivos; Ravi, Vilupanur A.; Star, Kurt E.; Fleurial, Jean Pierre; Liu, Zi-kui.
In: ACS Applied Energy Materials, Vol. 1, No. 11, 26.11.2018, p. 6600-6608.Research output: Contribution to journal › Article
TY - JOUR
T1 - Understanding the Intrinsic P-Type Behavior and Phase Stability of Thermoelectric α-Mg 3 Sb 2
AU - Chong, Xiaoyu
AU - Guan, Pin Wen
AU - Wang, Yi
AU - Shang, Shunli
AU - Paz Soldan Palma, Jorge
AU - Drymiotis, Fivos
AU - Ravi, Vilupanur A.
AU - Star, Kurt E.
AU - Fleurial, Jean Pierre
AU - Liu, Zi-kui
PY - 2018/11/26
Y1 - 2018/11/26
N2 - α-Mg 3 Sb 2 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 (V Mg(2) + Mg I ) 1- . The Mg solubility in α-Mg 3+x Sb 2 is quite small when only considering a single defect, but it enlarged up to x = 0.011 with the defect complex (V Mg(2) + Mg I ) 1- , which is more reasonable as supported by experiments. Under Mg-poor conditions, V Mg(1) 2- and V Mg(2) 2- are the dominant defects, and their concentrations can reach (1.05-1.18) × 10 19 cm -3 at 1200 K. Under Mg-rich conditions, (V Mg(2) + Mg I ) 1- is found to be the dominant reason for strong p-type behavior, and their concentrations can reach as high as 3.5 × 10 20 cm -3 , which shifts the Fermi level closer to the valence band maximum. The predicted carrier concentrations in the range 10 17 -10 20 cm -3 are in the same range found experimentally for pure p-type α-Mg 3 Sb 2 .
AB - α-Mg 3 Sb 2 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 (V Mg(2) + Mg I ) 1- . The Mg solubility in α-Mg 3+x Sb 2 is quite small when only considering a single defect, but it enlarged up to x = 0.011 with the defect complex (V Mg(2) + Mg I ) 1- , which is more reasonable as supported by experiments. Under Mg-poor conditions, V Mg(1) 2- and V Mg(2) 2- are the dominant defects, and their concentrations can reach (1.05-1.18) × 10 19 cm -3 at 1200 K. Under Mg-rich conditions, (V Mg(2) + Mg I ) 1- is found to be the dominant reason for strong p-type behavior, and their concentrations can reach as high as 3.5 × 10 20 cm -3 , which shifts the Fermi level closer to the valence band maximum. The predicted carrier concentrations in the range 10 17 -10 20 cm -3 are in the same range found experimentally for pure p-type α-Mg 3 Sb 2 .
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U2 - 10.1021/acsaem.8b01520
DO - 10.1021/acsaem.8b01520
M3 - Article
VL - 1
SP - 6600
EP - 6608
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
SN - 2574-0962
IS - 11
ER -