Pseudo-binary GeTe-rich Sb₂Te₃(GeTe)_n materials recently exhibited promising thermoelectric performance at intermediate temperatures (500–800 K), largely due to the intrinsically low lattice thermal conductivity coming from the discrete van der Waals gaps dispersed in a rhombohedral matrix. In this work, by alloying Ge with Pb and adjusting the molar ratio of GeTe/Sb₂Te₃ in the binary, we successfully modulated the crystal structure from rhombohedral Sb₂Te₃(GeTe)₁₇ to pseudo-cubic (Sb₂Te₃)_0.5(Ge_0.91Pb_0.09Te)_17.5 at room temperature, thus achieved higher electronic band degeneracy and electrical performance. High-resolution scanning transmission electron microscope (STEM) characterizations revealed the existence of high-density discrete van der Waals gaps (length ∼ 10–40 nm) along {111} equivalent planes in GeTe matrix; surprisingly, these planar defects appear quite stable in following annealing processes at 873 K unlike what literatures reported. Further elemental mapping suggests that the enrichment of Pb element around van der Waals gaps are possibly responsible to the formation and stabilization of these planar defects. Eventually, a figure of merit ZT_max ∼2.4 at 773 K and average ZT_avg ∼1.5 at 323–773 K were simultaneously realized in the (Sb₂Te₃)_0.5(Ge_0.91Pb_0.09Te)_17.5 sample after 4 days annealing at 873 K.

伪二元富含 GeTe 的 Sb ₂ Te ₃ (GeTe) _n材料最近在中间温度 (500–800 K) 下表现出有希望的热电性能，这主要是由于分散在菱形矩阵。在这项工作中，通过将 Ge 与 Pb 合金化并调整二元中 GeTe/Sb ₂ Te ₃的摩尔比，我们成功地将晶体结构从菱面体 Sb ₂ Te ₃ (GeTe) ₁₇调制为伪立方 (Sb ₂ Te ₃ ) _0.5 (Ge _0.91 Pb _0.09Te) _17.5在室温下，从而实现了更高的电子能带简并性和电学性能。高分辨率扫描透射电子显微镜 (STEM) 表征揭示了在 GeTe 基体中沿 {111} 等效平面存在高密度离散范德华间隙（长度 ∼ 10-40 nm）；令人惊讶的是，与文献报道的不同，这些平面缺陷在 873 K 的退火过程中显得非常稳定。进一步的元素映射表明，范德华间隙周围铅元素的富集可能是这些平面缺陷的形成和稳定的原因。最终，品质因数ZT _max ∼2.4 at 773 K 和平均ZT _avg在 873 K 下退火 4 天后，(Sb ₂ Te ₃ ) _0.5 (Ge _0.91 Pb _0.09 Te) _17.5样品在 323–773 K 下同时达到约 1.5 。