Exploring the Borders of the Zintl‐Klemm Concept: On the Isopunctual Phases Eu5+xMg18–xGe13(x = 0.1) and Eu8Mg16Ge12
Exploring the Borders of the Zintl‐Klemm Concept: On the Isopunctual Phases Eu5+xMg18–xGe13(x = 0.1) and Eu8Mg16Ge12
复制标题
探索 Zintl-Klemm 概念的边界：关于等点相 Eu5+xMg18–xGe13(x = 0.1) 和 Eu8Mg16Ge12
DOI：
10.1002/zaac.201200058
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
R. Nesper
中科院分区：
文献类型：
--
作者：
Adam Slabon;E. Cuervo;C. Kubata;C. Mensing;R. Nesper
用固相法合成了两个新的三元化合物Eu_（5 + x）Mg_（18-x）Ge_（13）（x = 0.1）和Eu_（8）Mg_（16）Ge_（12），用X射线单晶衍射法测定了它们的晶体结构。这两种化合物均为六方晶系（空间群P2 m）。Eu 5 + xMg 18-xGe 13（x = 0.1）是一个Zintl相，含有9个孤立的Ge 4-离子和一个[Ge 4]10-星星，它与PF 3等电子，但令人惊讶的是几乎是平面的。Eu 8 Mg 16 Ge 12含有[MGe 3]（M = Eu、Mg）单元，而不是[Ge 4]10-，可以描述为一种盐状化合物，含有12个“孤立的”Ge 4-阴离子。这两种化合物的结构相似性允许分析不同Zintl阴离子的化学键合，其属于结构更大的电子等排单元。Eu 8 Mg 16 Ge 12的金属导电性来源于沿着c方向的“所谓孤立”阴离子的黄道堆叠。在Eu 5 + xMg 18-xGe 13中，Zintl阴离子偏离平面性导致半金属行为。在这两种情况下，磁响应都是由铕原子的局部磁矩决定的，这些磁矩都是在2+氧化态下发现的。偏离居里-外斯定律观察到T < 20 K的阳离子更丰富的化合物和在其他较低的温度。低温区的行为随着[Ge 4]10-星星被MGe 3单元取代而改变。这些研究表明，通过黄道堆叠的平面阴离子的金属行为，甚至可以实现与单原子阴离子，高达4.4与锗至少，并可以被破坏的小偏差，从平面在扩展阴离子。
Two new ternary compounds Eu5+xMg18–xGe13 (x = 0.1) and Eu8Mg16Ge12 were obtained by solid state synthesis and their crystal structures determined by single crystal X-ray diffraction. The two compounds crystallize in the hexagonal crystal system (space group P2m). Eu5+xMg18–xGe13 (x = 0.1) is a Zintl phase with nine isolated Ge4– ions and a [Ge4]10– star, which is isoelectronic with PF3 but surprisingly almost planar. Eu8Mg16Ge12 contains a [MGe3] (M = Eu, Mg) unit, instead of the [Ge4]10–, and can be described as a salt-like compound, containing 12 “isolated” Ge4– anions. The structural similarity of these two compounds allows to analyze the chemical bonding of different Zintl anions, which belong to a structural greater isosteric unit. The metallic conductivity of Eu8Mg16Ge12 originates from the ecliptic stacking of the “so-called isolated” anions along the c direction. In Eu5+xMg18–xGe13 the deviation of the Zintl anion from the planarity causes a semi-metallic behavior. In both cases, the magnetic response is dominated by the local moments of the europium atoms, which are all found in a 2+ oxidation state. Deviations from the Curie–Weiss law are observed for T < 20 K in the cation-richer compound and at lower temperatures in the other. The behavior in the low-temperature range changes with the replacement of the [Ge4]10– star by the MGe3 unit. These studies show that metallic behavior through ecliptic stacking of planar anions can be achieved even with monatomic anions, up to 4.4 A with germanium at least, and can be destroyed by small deviations from planarity in an extended anion.
影响因子：
8.6
作者：
OHNO, H;MUNEKATA, H;CHANG, LL
通讯作者：
CHANG, LL