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Grain Boundary Scattering of Charge Transport in n‐Type (Hf,Zr)CoSb Half‐Heusler Thermoelectric Materials
Author(s) -
Qiu Qinyi,
Liu Yintu,
Xia Kaiyang,
Fang Teng,
Yu Junjie,
Zhao Xinbing,
Zhu Tiejun
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201803447
Subject(s) - materials science , thermoelectric effect , scattering , phonon scattering , condensed matter physics , grain boundary , thermoelectric materials , ionized impurity scattering , carrier scattering , charge carrier , seebeck coefficient , doping , thermal conductivity , optoelectronics , metallurgy , thermodynamics , composite material , microstructure , physics , optics
High thermoelectric figure of merit zT of ≈1.0 has been reported in both n‐ and p‐type (Hf,Zr)CoSb‐based half‐Heusler compounds, and further improvement of thermoelectric performance relies on the insightful understanding of electron and phonon transport mechanisms. In this work, the thermoelectric transport features are analyzed for (Hf 0.3 Zr 0.7 ) 1− x Nb x CoSb ( x = 0.02–0.3) with a wide range of carrier concentration. It is found that, although both temperature and energy dependencies of charge transport resemble ionized impurity scattering, the grain boundary scattering is the dominant scattering mechanism near room temperature. With increasing carrier concentration and grain size, the influence of the grain boundary scattering on electron transport weakens. The dominant scattering mechanism changes from grain boundary scattering to acoustic phonon scattering as temperature rises. The lattice thermal conductivity decreases with increasing Nb doping content due to the increased strain field fluctuations. These results provide an in‐depth understanding of the transport mechanisms and guidance for further optimizing thermoelectric properties of half‐Heusler alloys and other thermoelectric systems.