Abstract Highly disordered superionic phases lead to high thermoelectric performance (ZT~1.5) for Cu2M (M = S, Se, Te) alloys but bring challenges concerning thermal instability. Here we demonstrate that enhanced thermoelectric properties and improved thermal stability could be simultaneously realized in Cu2S through excessive I addition, mechanical alloying and radio-frequency (RF) hot pressing. The addition of excessive I beyond stoichiometric ratio not only induces higher Cu deficiency and thus better electrical properties for the prepared Cu2SIx (x = 0–0.15) alloys, but also leads to ultra-low thermal conductivity ascribed to multiple superionic phases and abundant nano-crystals. As a result, a ZT of 1.8 at 973 K is achieved for sample x = 0.10 (Cu2SI0.1), which is nearly twice the value of undoped Cu2S. Moreover, excessive I addition eliminates the ultrafast phase transformation that results in abrupt volume changes in pristine Cu2S and suppresses the rest transformations to be very sluggish. The high ZT value together with significantly suppressed phase transitions and impeded copper segregation enable the excessively I-added samples more beneficial for practical thermoelectric power generation.

中文翻译：

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过量的碘添加导致室温超离子 Cu2S 具有增强的热电性能和改善的热稳定性

摘要 高度无序的超离子相导致 Cu2M (M = S, Se, Te) 合金具有较高的热电性能 (ZT~1.5)，但也带来了热不稳定性方面的挑战。在这里，我们证明了通过过量的 I 添加、机械合金化和射频 (RF) 热压，可以在 Cu2S 中同时实现增强的热电性能和改善的热稳定性。添加超过化学计量比的过量 I 不仅会导致更高的 Cu 缺陷，从而导致制备的 Cu2SIx (x = 0-0.15) 合金具有更好的电性能，而且还会导致超低热导率归因于多个超离子相和丰富的纳米级晶体。因此，样品 x = 0.10 (Cu2SI0.1) 在 973 K 下的 ZT 为 1.8，几乎是未掺杂 Cu2S 值的两倍。而且，过量的 I 添加消除了导致原始 Cu2S 体积突然变化的超快相变，并抑制了其余相变变得非常缓慢。高 ZT 值以及显着抑制的相变和阻碍的铜偏析使过量添加 I 的样品更有利于实际热电发电。