TY - JOUR
T1 - Half-Heusler thermoelectric materials
T2 - NMR studies
AU - Tian, Yefan
AU - Ghassemi, Nader
AU - Ren, Wuyang
AU - Zhu, Hangtian
AU - Li, Shan
AU - Zhang, Qian
AU - Wang, Zhiming
AU - Ren, Zhifeng
AU - Ross, Joseph H.
N1 - Publisher Copyright:
© 2020 Author(s).
PY - 2020/8/7
Y1 - 2020/8/7
N2 - We report 59 Co, 93 Nb, and 121 Sb nuclear magnetic resonance measurements combined with density functional theory (DFT) calculations on a series of half-Heusler semiconductors, including NbCoSn, ZrCoSb, TaFeSb, and NbFeSb, to better understand their electronic properties and general composition-dependent trends. These materials are of interest as potentially high efficiency thermoelectric materials. Compared to the other materials, we find that ZrCoSb tends to have a relatively large amount of local disorder, apparently antisite defects. This contributes to a small excitation gap corresponding to an impurity band near the band edge. In NbCoSn and TaFeSb, Curie-Weiss-type behavior is revealed, which indicates a small density of interacting paramagnetic defects. Very large paramagnetic chemical shifts are observed associated with a Van Vleck mechanism due to closely spaced d bands splitting between the conduction and valence bands. Meanwhile, DFT methods were generally successful in reproducing the chemical shift trend for these half-Heusler materials, and we identify enhancement of the larger-magnitude shifts, which we connect to electron interaction effects. The general trend is connected to changes in d-electron hybridization across the series.
AB - We report 59 Co, 93 Nb, and 121 Sb nuclear magnetic resonance measurements combined with density functional theory (DFT) calculations on a series of half-Heusler semiconductors, including NbCoSn, ZrCoSb, TaFeSb, and NbFeSb, to better understand their electronic properties and general composition-dependent trends. These materials are of interest as potentially high efficiency thermoelectric materials. Compared to the other materials, we find that ZrCoSb tends to have a relatively large amount of local disorder, apparently antisite defects. This contributes to a small excitation gap corresponding to an impurity band near the band edge. In NbCoSn and TaFeSb, Curie-Weiss-type behavior is revealed, which indicates a small density of interacting paramagnetic defects. Very large paramagnetic chemical shifts are observed associated with a Van Vleck mechanism due to closely spaced d bands splitting between the conduction and valence bands. Meanwhile, DFT methods were generally successful in reproducing the chemical shift trend for these half-Heusler materials, and we identify enhancement of the larger-magnitude shifts, which we connect to electron interaction effects. The general trend is connected to changes in d-electron hybridization across the series.
UR - http://www.scopus.com/inward/record.url?scp=85089307651&partnerID=8YFLogxK
U2 - 10.1063/5.0018260
DO - 10.1063/5.0018260
M3 - 文章
AN - SCOPUS:85089307651
SN - 0021-8979
VL - 128
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 5
M1 - 055106
ER -