New materials have been playing a continuously more important role in advancing thermoelectric technology. Many known novel thermoelectric materials share the similarity of an intrinsic low lattice thermal conductivity (κ_L) due to various mechanisms. Because heat is generally conducted by acoustic phonons because of the much higher velocities as compared to those of optical phonons, many known low-κ_L thermoelectrics rely on the complexity of crystal structure to lead the fraction of acoustic phonons to be small. In addition to structural complexity, an overall low sound velocity is found to be helpful for realizing an extremely low κ_L. In this work, a new thermoelectric compound Ag_5−δTe₃, having both a complex crystal structure and a low sound velocity (∼1300 m/s), is shown to be one of the least thermally conductive dense solids (κκ_L ∼ 0.2 W/m·K). The resultant high thermoelectric figure of merit, zT, of unity, with the help of its large band gap of ∼0.6 eV, leads this material to be superior to known silver tellurides. These preliminary results demonstrate Ag_5−δTe₃ as a promising thermoelectric material, with possibilities for further improvements particularly through enhancements focusing on electronic properties.

中文翻译：

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具有固有的低格导热性的有前途的热电Ag _5−δ Te ₃

新材料在发展热电技术中一直扮演着越来越重要的角色。许多已知的新颖热电材料共享一个固有的低晶格热导率（κ的相似度_大号）由于各种机制。因为热量通常由因为高得多的速度的声子传导相比，这些光学声子的，许多已知的低κ_大号热电依靠晶体结构的复杂性导致的声学声子的分数为较小。除了结构复杂，整体低音速被发现是实现极低的κ有益的_大号。在这项工作中，一种新的热电化合物Ag _5−δ Te ₃，同时具有复杂的晶体结构以及低的声速（~1300米/秒），被示为最小导热致密固体中的一个（κκ_大号〜0.2瓦/米·K）。凭借其高的〜0.6 eV的带隙，所得的高热电品质因数zT为1，使该材料优于已知的碲化银。这些初步结果表明，Ag _5–δ Te ₃是一种很有前途的热电材料，尤其是通过专注于电子性能的增强，有可能进一步改进。