TY - JOUR
T1 - The Mechanism behind the High Thermoelectric Performance in YbCd2-xMgxSb2
AU - Kwon, Seung Hwan
AU - Kim, Sang Il
AU - Heo, Minsu
AU - Seo, Won Seon
AU - Roh, Jong Wook
AU - Yang, Heesun
AU - Kim, Hyun Sik
N1 - Publisher Copyright:
Copyright © The Korean Institute of Metals and Materials.
PY - 2023/3
Y1 - 2023/3
N2 - YbCd2Sb2 is a promising Zintl compound for waste heat recovery applications due to its low thermal conductivity, originating from its complex crystal structure. Many strategies such as alloying or doping have been suggested to further reduce the thermal conductivity of YbCd2Sb2 to improve its thermoelectric performance. However, the effects of alloying or doping on the electronic transport properties of YbCd2Sb2 have not been evaluated in detail. Here, previously reported thermoelectric properties of YbCd2-xMgxSb2 (x = 0, 0.2, 0.4) with drastic thermal conductivity suppression were evaluated using the Single Parabolic Band (SPB) model and Callaway von Bayer (CvB) model. The SPB and CvB models evaluate any changes in electronic band parameters and phonon scattering strength, respectively, due to Mg alloying. Based on the SPB model, Mg alloying deteriorated the weighted mobility, mostly due to non-degenerate mobility reduction. However, the magnitude of point-defect phonon scattering significantly increased with Mg alloying, as evaluated by the CvB model. As a result, the maximum zT is achieved when x = 0.4 at 700 K despite the decreased electronic transport properties from Mg alloying. Our work suggests that carefully designed alloying can improve the thermoelectric performance of the Zintl compound even when it changes its electronic and thermal transport properties in opposite directions.
AB - YbCd2Sb2 is a promising Zintl compound for waste heat recovery applications due to its low thermal conductivity, originating from its complex crystal structure. Many strategies such as alloying or doping have been suggested to further reduce the thermal conductivity of YbCd2Sb2 to improve its thermoelectric performance. However, the effects of alloying or doping on the electronic transport properties of YbCd2Sb2 have not been evaluated in detail. Here, previously reported thermoelectric properties of YbCd2-xMgxSb2 (x = 0, 0.2, 0.4) with drastic thermal conductivity suppression were evaluated using the Single Parabolic Band (SPB) model and Callaway von Bayer (CvB) model. The SPB and CvB models evaluate any changes in electronic band parameters and phonon scattering strength, respectively, due to Mg alloying. Based on the SPB model, Mg alloying deteriorated the weighted mobility, mostly due to non-degenerate mobility reduction. However, the magnitude of point-defect phonon scattering significantly increased with Mg alloying, as evaluated by the CvB model. As a result, the maximum zT is achieved when x = 0.4 at 700 K despite the decreased electronic transport properties from Mg alloying. Our work suggests that carefully designed alloying can improve the thermoelectric performance of the Zintl compound even when it changes its electronic and thermal transport properties in opposite directions.
KW - YbCdSb
KW - callaway von bayer model
KW - single parabolic band model
KW - zintl phase
UR - http://www.scopus.com/inward/record.url?scp=85152390415&partnerID=8YFLogxK
U2 - 10.3365/KJMM.2023.61.3.198
DO - 10.3365/KJMM.2023.61.3.198
M3 - Article
AN - SCOPUS:85152390415
SN - 1738-8228
VL - 61
SP - 198
EP - 205
JO - Journal of Korean Institute of Metals and Materials
JF - Journal of Korean Institute of Metals and Materials
IS - 3
ER -