Wu Xiaowei, Fan Zhen, Zhu Hangtian, Wang Tianyu, Liu Meng, Li Jun, Chen Nan, Liu Qiulin, Lu Zhen, Li Guodong, Qian Xin, Liu Te-Huan, Yang Ronggui, Niu Xiaoyan, Zhao Qi, Li Zhiliang, Wang Shufang, Zhao Huaizhou
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
School of Physical Science, University of Chinese Academy of Sciences, Beijing, China.
Nat Commun. 2025 Apr 14;16(1):3534. doi: 10.1038/s41467-025-58491-1.
Bi-Sb alloy, as a promising thermoelectric material at cryogenic temperatures, has seen stagnant progress due to challenges in understanding the transport behaviors of energy carriers, and difficulties in synthesizing high-homogeneity, large-grain samples. In this study, an inherent electron-phonon decoupling in Bi-Sb is revealed using the first-principles calculations based on the virtual crystal approximation. The mean free path of the dominant electrons (λ ~ 10 nm) is found of two orders of magnitude larger than that of phonons (λ ~ 10nm), suggesting that a grain size greater than 10 μm would be favorable for thermoelectric transport. Bulk Bi-Sb polycrystals with highly elemental homogeneity and large grain size (~80 μm) are successfully synthesized through an ultra-fast quenching method combined with annealing, delivering superior thermoelectric performance. A prototype module based on the BiSb polycrystal, with a ZT of 0.48 at 150 K, is fabricated and demonstrates a ΔT of 4 K at a T of 75 K. This marks the first report of n-p paired thermoelectric cooling modules operating below liquid nitrogen temperature.
Bi-Sb合金作为一种在低温下很有前景的热电材料，由于在理解能量载流子的输运行为方面存在挑战，以及在合成高均匀性、大晶粒样品方面存在困难，其进展一直停滞不前。在本研究中，基于虚拟晶体近似的第一性原理计算揭示了Bi-Sb中固有的电子-声子解耦。发现主导电子的平均自由程（λ ~ 10 nm）比声子的平均自由程（λ ~ 10nm）大两个数量级，这表明大于10μm的晶粒尺寸有利于热电输运。通过超快淬火法结合退火成功合成了具有高度元素均匀性和大晶粒尺寸（~80μm）的块状Bi-Sb多晶体，其具有优异的热电性能。制造了一个基于BiSb多晶体的原型模块，在150K时ZT为0.48，并在75K的温度下表现出4K的温差。这标志着首次报道了在液氮温度以下运行的n-p对热电冷却模块。
