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arXiv 2303.03062cond-mat.mtrl-scicond-mat.str-el
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金属NiAu合金中的高热电性能

High thermoelectric performance in metallic NiAu alloys

Fabian Garmroudi, Michael Parzer, Alexander Riss, Cédric Bourgès, Sergii Khmelevskyi, Takao Mori, Ernst Bauer, Andrej Pustogow

AI总结:

本文通过调控能量依赖的电子散射,在二元NiAu合金中实现了高达34 mWm⁻¹K⁻²的功率因子和0.5的zT值,刷新金属热电性能纪录,证明利用s-d选择性散射可在金属中实现高效热电转换。

摘要:

热电(TE)材料能够将热能无缝转换为电能,反之亦然,因此在发电或制冷等应用中具有广阔前景。尽管历史上热电效应最早是在金属中发现的,但当前最先进的研究主要集中于具有大优值系数$zT$的掺杂半导体,$zT$决定了热电设备的转换效率。虽然金属合金具有优异的力学性能,如高延展性和机械强度,但由于其塞贝克效应较小,过去大多被排除在研究之外。在此,我们通过调控能量依赖的电子散射,在金属中实现了前所未有的热电性能。基于我们的理论预测,我们确定二元NiAu合金为有前景的候选材料,并通过实验发现了高达34 mWm$^{-1}$K$^{-2}$的巨大功率因子(在300至1100 K范围内平均为30 mWm$^{-1}$K$^{-2}$),这比室温以上任何已知块体材料高出两倍以上。该体系的$zT$值达到0.5,创下了金属材料的新世界纪录。NiAu合金不仅比重掺杂半导体的导电性高出数个数量级,而且具有源自本质上不同物理机制的大塞贝克系数:在Au的s能带内,传导电子具有高迁移率,而空穴被散射到更局域化的Ni d态,从而产生强烈依赖能量的载流子迁移率。我们的工作挑战了“良金属即差热电材料”的普遍观念,并展示了一种通过工程化电子-空穴选择性s-d散射在金属合金中实现高热电性能的有前景的范式。

英文摘要:

Thermoelectric (TE) materials seamlessly convert thermal into electrical energy and vice versa, making them promising for applications such as power generation or cooling. Although historically the TE effect was first discovered in metals, state-of-the-art research mainly focuses on doped semiconductors with large figure of merit, $zT$, that determines the conversion efficiency of TE devices. While metallic alloys have superior functional properties, such as high ductility and mechanical strength, they have mostly been discarded from investigation in the past due to their small Seebeck effect. Here, we realize unprecedented TE performance in metals by tuning the energy-dependent electronic scattering. Based on our theoretical predictions, we identify binary NiAu alloys as promising candidate materials and experimentally discover colossal power factors up to 34 mWm$^{-1}$K$^{-2}$ (on average 30 mWm$^{-1}$K$^{-2}$ from 300 to 1100 K), which is more than twice larger than in any known bulk material above room temperature. This system reaches a $zT$ up to 0.5, setting a new world record value for metals. NiAu alloys are not only orders of magnitude more conductive than heavily doped semiconductors, but also have large Seebeck coefficients originating from an inherently different physical mechanism: within the Au s band conduction electrons are highly mobile while holes are scattered into more localized Ni d states, yielding a strongly energy-dependent carrier mobility. Our work challenges the common belief that good metals are bad thermoelectrics and presents an auspicious paradigm for achieving high TE performance in metallic alloys through engineering electron-hole selective s-d scattering.

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