Key Laboratory for Macromolecular Science of Shaanxi Province, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.
State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
Small. 2023 Apr;19(17):e2206439. doi: 10.1002/smll.202206439. Epub 2023 Jan 26.
GeTe-based pseudo-binary (GeTe) (AgSbTe ) (TAGS-x) is recognized as a promising p-type mid-temperature thermoelectric material with outstanding thermoelectric performance; nevertheless, its intrinsic structural transition and metastable microstructure (due to Ag/Sb/Ge localization) restrict the long-time application of TAGS-x in practical thermoelectric devices. In this work, a series of non-stoichiometric (GeTe) (Ag Sb Te ) (x = 85∼50; δ = ≈0.20-0.23), referred to as δ-TAGS-x, with all cubic phase over the entire testing temperature range (300-773 K), is synthesized. Through optimization of crystal symmetry and microstructure, a state-of-the-art ZT of 1.86 at 673 K and average ZT of 1.43 at ≈323-773 K are realized in δ-TAGS-75 (δ = 0.21), which is the highest value among all reported cubic-phase GeTe-based thermoelectric systems so far. As compared with stoichiometric TAGS-x, the remarkable thermoelectric achieved in cubic δ-TAGS-x can be attributed to the alleviation of highly (electrical and thermal) resistive grain boundary Ag GeTe phase. Moreover, δ-TAGS-x exhibits much better mechanical properties than stoichiometric TAGS-x, together with the outstanding thermoelectric performance, leading to a robust single-leg thermoelectric module with η of ≈10.2% and P of ≈0.191 W. The finding in this work indicates the great application potential of non-stoichiometric δ-TAGS-x in the field of mid-temperature waste heat harvesting.
基于 GeTe 的伪二元 (GeTe) (AgSbTe ) (TAGS-x) 被认为是一种很有前途的 p 型中温热电材料，具有优异的热电性能；然而，其本征结构转变和亚稳的微结构（由于 Ag/Sb/Ge 定位）限制了 TAGS-x 在实际热电设备中的长时间应用。在这项工作中，合成了一系列非化学计量比的 (GeTe) (Ag x Sb y Te z ) (x = 85∼50; δ = ≈0.20-0.23)，称为 δ-TAGS-x，在整个测试温度范围内（300-773 K）都具有全部立方相。通过优化晶体对称性和微结构，在 δ-TAGS-75（δ = 0.21）中实现了在 673 K 时的卓越 ZT 值 1.86 和在 ≈323-773 K 时的平均 ZT 值 1.43，这是迄今为止所有报道的基于立方相 GeTe 的热电系统中的最高值。与化学计量比的 TAGS-x 相比，立方 δ-TAGS-x 中实现的显著热电性能可归因于高度（电和热）电阻的晶界 Ag GeTe 相的缓解。此外，δ-TAGS-x 的机械性能比化学计量比的 TAGS-x 要好得多，同时具有出色的热电性能，导致具有约 10.2%的 η和约 0.191 W 的 robust 单腿热电模块。这项工作的发现表明，非化学计量比的 δ-TAGS-x 在中温废热回收领域具有巨大的应用潜力。
