2022-Sustainable Industrial Processing Summit
SIPS2022 Volume 9 Mizutani Intl. Symp. Science of Intelligent & Advanced Materials (SISAM) and Quasi-crystals
| Editors: | F. Kongoli, J. Dubois, E. Gaudry, T. Homma, V. Fournee |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2022 |
| Pages: | 116 pages |
| ISBN: | 978-1-989820-50-6(CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Huge enhancement of thermoelectric dimensionless figure of merit in (Ag,Cu)2(S,Se,Te) and their electric power generation
Tsunehiro Takeuchi1;1TOYOTA TECHNOLOGICAL INSTITUTE, Nagoya, Japan;
Type of Paper: Invited
Id Paper: 377
Topic: 42
Abstract:
Recently, a huge magnitude of Seebeck coefficient was observed for metallic Cu2Se under an unusual temperature gradient produced by an experimental set up consisting of the two-heaters. This material is characterized by a structure phase transition at about 400 K. Two heaters placed at the bottom and one side of sample produced a layered composite consisting of the low temperature phase (LTP) at the top surface and the high temperature phase (HTP) in the bottom. The composition of LTP varied with varying temperature during the phase transition, and eventually it became an insulator only in a very narrow temperature range. The insulating LTP staying on the metallic HTP allowed us to observe a large magnitude of Seebeck coefficient S exceeding a few mVK-1 and rather small magnitude of electrical resistivity ρ as low as 1 mΩcm. These numbers led to a huge value of power factor PF = S2σ exceeding a few mWm-1K-2. Together with the small lattice thermal conductivity in association with the anharmonic lattice vibration, the dimensionless figure of merit ZT were increased to a surprisingly large value exceeding 470. [1]
The variation of composition with varying temperature in the Cu2Se LTP limits the large ZT-value only in a very narrow temperature range of a few K in width near 350 K, and this condition has prohibited us from utilizing it in practical applications. The problem about the narrow temperature range was eliminated by employing Ag2S that also possess a structure phase transition between insulating low temperature phase and metallic high temperature phase. Despite that the magnitude of ZT was reduced to 20, the temperature width of the large ZT-value was extended to 40 K (390 K ≤ T ≤ 430 K). [2]
The power generation from Ag2S was also confirmed in the steady state condition, and the enhancement of power generation was found to appear above 390 K where ZT-value was strongly increased.
The new phenomena introduced in this presentation provides us with a breakthrough in the technologies of thermoelectric power generation to contribute the construction of a low-energy-consuming, sustainable carbon neutral society.
Keywords:
Alloys; Atomic structures; Electronic structures; Energy applications; Thermoelectrics;References:
[1] D. Byeon et al., Nat. Comm.10, 1-7 (2019).[2] G. Kim et al., J. Phys. D: Appl. Phys. 54, 115503 (2021).