Thermoelectric properties of EuZn2Sb2 Zintl compounds: zT enhancement through Yb substitution for Eu
| Autor: | Yukihiro Isoda, Alex Zevalkink, Ikuzo Kanazawa, Yoshiki Takagiwa, Y. Sato, Kaoru Kimura, Yoshikazi Shinohara |
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| Rok vydání: | 2017 |
| Předmět: |
Electron mobility
Materials science Chemical substance Phonon Scattering Mechanical Engineering Metals and Alloys Analytical chemistry Nanotechnology 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Thermal conductivity Mechanics of Materials Electrical resistivity and conductivity Thermoelectric effect Materials Chemistry 0210 nano-technology Science technology and society |
| Zdroj: | Journal of Alloys and Compounds. 703:73-79 |
| ISSN: | 0925-8388 |
| DOI: | 10.1016/j.jallcom.2017.01.350 |
| Popis: | AZn2Sb2 (A: Ca, Sr, Eu, Yb) Zintl compounds have shown excellent thermoelectric performance peaking around 700 K. Among these materials, EuZn2Sb2 and YbZn2Sb2 compounds have the highest carrier mobility, making them particularly interesting. We present the thermoelectric properties of EuδZn2Sb2 (δ = 0.9, 1.0, 1.1) and Eu1-xYbxZn2Sb2 compounds (x = 0, 0.1, 0.25, 0.5, 0.75, 1) from 373 to 773 K. Our interest is in studying whether introducing A-site vacancies increases the hole carrier concentration with decreasing Eu content or with increasing Yb substitution, which could lead to optimized power factor at high temperatures. The electrical conductivity showed a non-monotonic change caused by carrier mobility scattering. The thermal conductivity decreased through deviation of the Eu content and through Eu-Yb substitution; in particular, the phonon contribution at 773 K reduced gradually from 1.1 W m−1 K−1 (x = 0) to 0.42 W m−1 K−1 (x = 1.0) with increasing Yb fraction and reached the predicted minimum lattice thermal conductivity. The dimensionless figure of merit increased from 0.58 to 0.68 at 773 K through a 10% Yb substitution, i.e. Eu0.9Yb0.1Zn2Sb2, mainly due to the reduction of phonon thermal conductivity without lowering the power factor. |
| Databáze: | OpenAIRE |
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