Two new quaternary compounds, Ba₂₃Ga₁₀Ge₁₀Sb₂₅ and Ba₂₃In₁₀Ge₁₀Sb_24.79, have been synthesized by using the high temperature solid-state reactions. These new phases exhibit huge unit cells (V = 17 514.6 and 18 455.8 ų for Ga- and In-containing compounds, respectively),which comprise 544 atoms and feature “onion-like” M₂₀Ge₂₀Sb₃₀ clusters connected through the Sb–Sb bonds. Among these clusters, substantial isolated units such as Ba, Sb, or Sb₃ trimers are filled. With such a complex structure as well as the large unit cell and substantial heavy constituent atoms, ultralow lattice thermal conductivity (κ_l) was observed for Ba₂₃Ga₁₀Ge₁₀Sb₂₅, ranging from 0.2 to 0.38 W·m^–1·K^–1 from 323 to 823 K. As a result, a maximun ZT of 0.27 was achieved at 823 K.

中文翻译：

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Ba ₂₃ M ₁₀ Ge ₁₀ Sb25 _-δ（M = Ga，In）中的超低晶格导热率：包含以Ba为中心的十二面体的四元化合物

利用高温固相反应合成了两种新的季铵化合物Ba ₂₃ Ga ₁₀ Ge ₁₀ Sb ₂₅和Ba ₂₃ In ₁₀ Ge ₁₀ Sb _24.79。这些新的阶段表现出巨大的单元电池（V = 17 514.6和18 455.8埃³为含In GA-和化合物，分别地），其包含544个原子和特征“洋葱状” M ₂₀的Ge ₂₀ Sb的_30个通过连接簇Sb–Sb债券。在这些簇中，大量孤立的单元（例如Ba，Sb或Sb _3）三聚体被填充。根据这样的结构复杂，以及大单元细胞和大量的重构成原子，超低晶格热导率（κ_升）中观察到Ba的₂₃镓₁₀的Ge ₁₀ Sb的₂₅，为0.2至0.38·W·米^-1 ·K从323到823 K时为^–1。结果，在823 K时获得的最大ZT为0.27。