气候变化领域集成服务门户(CCPortal): Systematic over-estimation of lattice thermal conductivity in materials with electrically-resistive grain boundaries

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DOI	10.1039/c9ee03921j
	Systematic over-estimation of lattice thermal conductivity in materials with electrically-resistive grain boundaries
	Kuo J.J.; Wood M.; Slade T.J.; Kanatzidis M.G.; Snyder G.J.
发表日期	2020
ISSN	17545692
起始页码	1250
结束页码	1258
卷号	13 期号:4
英文摘要	Reducing the thermal conductivity κ of a material via nano-structuring to create small grain sizes is one of the most common strategies to improve thermoelectric materials. In such polycrystalline materials heat carrying phonons are scattered at the grain boundaries, which directly improves the thermoelectric quality factor and ultimately the figure-of-merit zT. In some cases, however, such as in Mg3Sb2, SnSe, and Mg2Si an opposite trend is found where higher lattice thermal conductivity reported in small grain polycrystalline material than in large grain or single crystal materials. This unphysical result indicates a problem with the conventional use of the Wiedemann-Franz law. Here, we trace this problematic finding to the electrical resistance at the grain boundaries, which leads to an overestimation of the phonon or lattice contribution of the thermal conductivity κL. In materials with significant grain boundary electrical resistance, the estimated electronic contribution to the thermal conductivity LσT is low because the measured electrical conductivity σ is low. However within the grain electrons may still be transporting more heat than the total conductivity suggests, leading to an overestimation of κL if the conventional κL = κ-LσT is used with the measured values of κ and σ. The overestimation of κL in small-grain samples is shown to be pervasive across a broad range of thermoelectric materials, including Mg3Sb2, Mg2Si, PbTe, PbSe, SnSe, (Hf,Zr)CoSb, CoSb3, and Bi2Te3 alloys, and a correction is necessary to properly understand and predict their charge and heat transport. © The Royal Society of Chemistry.
英文关键词	Bismuth alloys; Bismuth compounds; Cobalt alloys; Crystal lattices; Electric resistance; Grain boundaries; IV-VI semiconductors; Layered semiconductors; Phonons; Polycrystalline materials; Silicon; Single crystals; Thermoelectric equipment; Thermoelectricity; Tin compounds; Zircaloy; Electrical conductivity; Electrical resistances; Electronic contributions; Heat carrying phonons; Lattice contribution; Lattice thermal conductivity; Single-crystal materials; Thermo-Electric materials; Thermal conductivity; electrical conductivity; electron; estimation method; thermal conductivity
语种	英语
来源期刊	Energy & Environmental Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/189662
作者单位	Northwestern University, Evanston, IL 60208, United States
推荐引用方式 GB/T 7714	Kuo J.J.,Wood M.,Slade T.J.,et al. Systematic over-estimation of lattice thermal conductivity in materials with electrically-resistive grain boundaries[J],2020,13(4).
APA	Kuo J.J.,Wood M.,Slade T.J.,Kanatzidis M.G.,&Snyder G.J..(2020).Systematic over-estimation of lattice thermal conductivity in materials with electrically-resistive grain boundaries.Energy & Environmental Science,13(4).
MLA	Kuo J.J.,et al."Systematic over-estimation of lattice thermal conductivity in materials with electrically-resistive grain boundaries".Energy & Environmental Science 13.4(2020).