Stabilization and high thermoelectric performance of high-entropy-type cubic AgBi(S, Se, Te)2

Asato Seshita; Aichi Yamashita; Takeshi Fujita; Takayoshi Katase; Akira Miura; Yuki Nakahira; Chikako Moriyoshi; Yoshihiro Kuroiwa; Yoshikazu Mizuguchi

arXiv · 2404.00984

Stabilization and high thermoelectric performance of high-entropy-type cubic AgBi(S, Se, Te)2

Asato Seshita·Aichi Yamashita·Takeshi Fujita·Takayoshi Katase·Akira Miura·Yuki Nakahira·Chikako Moriyoshi·Yoshihiro Kuroiwa·Yoshikazu Mizuguchi

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Abstract

As thermoelectric generators can convert waste heat into electricity, they play an important role in energy harvesting. The metal chalcogenide AgBiSe2 is one of the high-performance thermoelectric materials with low lattice thermal conductivity (klat), but it exhibits temperature-dependent crystal structural transitions from hexagonal to rhombohedral, and finally a cubic phase as the temperature rises. The high figure-of-merit ZT is obtained only for the high-temperature cubic phase. In this study, we utilized the high-entropy-alloy (HEA) concept for AgBiSe2 to stabilize the cubic phase throughout the entire temperature range with enhanced thermoelectric performance. We synthesized high-entropy-type AgBiSe2-2xSxTex bulk polycrystals and realized the stabilization of the cubic phase from room temperature to 800 K for x > 0.6. The ultra-low klat at of 0.30 Wm^-1K^-1 and the high peak ZT 0.9 at around 750 K were realized for cubic AgBiSe2-2xSxTex without carrier tuning. In addition, the average ZT value of x = 0.6 and 0.7 for the temperature range of 360-750 K increased to 0.38 and 0.40, respectively, which are comparable to the highest previously reported values.

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Asato Seshita, Aichi Yamashita, Takeshi Fujita, Takayoshi Katase, Akira Miura, Yuki Nakahira, Chikako Moriyoshi, Yoshihiro Kuroiwa, Yoshikazu Mizuguchi. 2024-04-01. Stabilization and high thermoelectric performance of high-entropy-type cubic AgBi(S, Se, Te)2. https://arxiv.org/abs/2404.00984

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