Five Zintl phases in the ternary system Eu–M–Pn (M = Al, In; Pn = As, Sb, Bi) were prepared from the elements in tantalum containers. Eu₅In₂As₆ and Eu₅In₂Sb₆ crystallize in the orthorhombic Ca₅Ga₂As₆ type structure (Pbam, oP26), while Eu₅In₂Bi₆ is isostructural to orthorhombic Ca₅Al₂Bi₆ (Pbam, oP26). Eu₃AlAs₃ adopts a monoclinic structure type (P2₁/c, mP28), which is isopointal to Rb₃TlO₃, and Eu₃GaAs₃ (Cmce, oS56), finally, crystallizes in the orthorhombic Ba₃AlSb₃ type structure. All structures have been refined from single crystal X-ray diffraction experiments and can be considered to be Zintl phases with a valence precise sum formula according to (Eu²⁺)₅(In³⁺)₂(Pn³⁻)₄(Pn²⁻)₂ and (Eu²⁺)₃(M³⁺)(As³⁻)₃. They all feature [MPn₄] tetrahedra, which are connected in different ways. While in the Ca₅Ga₂As₆ and Ca₅Al₂Bi₆ type representatives double strands via Pn–Pn bonds are formed, in Eu₃AlAs₃ and Eu₃GaAs₃, [M₂As₆]⁶⁻ tetrahedral dimers exist. The divalent europium atoms are located in between the chains, providing electroneutrality. The magnetic properties of four compounds have been investigated and complex (antiferro)magnetic ordering has been observed at T_N = 16.1(1) (Eu₅In₂As₆), 17.8(1) K (Eu₅In₂Sb₆), 10.0(1) K (Eu₃AlAs₃) and 10.7(1) K (Eu₃GaAs₃). The effective magnetic moment and ¹⁵¹Eu Mössbauer spectroscopic investigations unambiguously proved the divalent character of the Eu atoms. The spectra recorded below the magnetic ordering showed a (full) hyperfine field splitting. Additionally, ¹²¹Sb Mössbauer spectroscopic studies have been conducted on the antimonide Eu₅In₂Sb₆. Finally, computational studies of Eu₃AlAs₃ and Eu₅In₂Sb₆ indicate semiconducting behavior for the arsenide with a bandgap of ca. 1 eV, while an increased metallicity, manifested in a pseudo gap for the antimonide, is visible at the Fermi level.

中文翻译：

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关于在Zintl三元相Eu5In2Pn6和Eu3MAs3中的Eu原子的二价特性（Pn = As–Bi; M = Al，Ga）

由钽容器中的元素制备了三元体系Eu–M–Pn中的五个Zintl相（M = Al，In； Pn = As，Sb，Bi）。Eu ₅ In ₂ As ₆和Eu ₅ In ₂ Sb ₆在斜方晶Ca ₅ Ga ₂ As ₆型结构（Pbam，oP 26）中结晶，而Eu ₅ In ₂ Bi ₆与斜方晶Ca ₅ Al ₂ Bi _6等结构（Pbam，oP 26）。Eu ₃ AlAs ₃采用单斜结构式（P 2 ₁ / ç，mP在28），这是isopointal与Rb ₃ T10中₃和Eu _3层的GaAs ₃（CMCE，OS 56），最后，正交晶的Ba ₃的AlSb ₃型结构。所有结构均通过单晶X射线衍射实验精制而成，可以视为具有（Eu ²⁺）₅（In ³⁺）₂（Pn ³⁻）₄（Pn ）的价精确和公式的Zintl相。²⁻） ₂和（Eu ²⁺） ₃（M ³⁺）（As ³⁻） ₃。它们都具有[MPn ₄ ]四面体，它们以不同的方式连接。在Ca ₅ Ga ₂ As ₆和Ca ₅ Al ₂ Bi ₆型代表中，通过Pn-Pn键形成双链，而在Eu ₃ AlAs ₃和Eu ₃ GaAs _3中，[M ₂ As ₆ ] ⁶⁻存在四面体二聚体。二价euro原子位于链之间，提供电子中性。研究了四种化合物的磁性，并在T _N = 16.1（1）（Eu ₅ In ₂ As ₆），17.8（1）K（Eu ₅ In ₂ Sb ₆）， 10.0（1）K（Eu ₃ AlAs ₃）和10.7（1）K（Eu ₃ GaAs ₃）。有效磁矩与¹⁵¹EuMössbauer光谱学研究清楚地证明了Eu原子的二价特征。磁序下方记录的光谱显示（完整）超精细场分裂。此外，对锑化物Eu ₅ In ₂ Sb ₆进行了¹²¹ SbMössbauer光谱研究。最后，Eu ₃ AlAs ₃和Eu ₅ In ₂ Sb _6的计算研究表明，带隙约为ca的砷化物的半导体行为。在费米能级上可以看到1 eV，而在锑的假间隙中表现出的金属性增加。