We report a new quasi-one-dimensional compound KMn6Bi5 composed of parallel nanowires crystallizing in a monoclinic space group C2/ m with a = 22.994(2) Å, b = 4.6128(3) Å, c = 13.3830(13) Å and β = 124.578(6)°. The nanowires are infinite [Mn6Bi5]- columns each of which is composed of a nanotube of Bi atoms acting as the cladding with a nanorod of Mn atoms located in the central axis of the nanotubes. The nanorods of Mn atoms inside the Bi cladding are stabilized by Mn-Mn bonding and are defined by distorted Mn-centered cluster icosahedra of Mn13 sharing their vertices along the b axis. The [Mn6Bi5]- nanowires are linked with weak internanowire Bi-Bi bonds and charge balanced with K+ ions. The [Mn6Bi5]- nanowires were directly imaged by high-resolution transmission electron microscopy and scanning transmission electron microscopy. Magnetic susceptibility studies show one-dimensional characteristics with an antiferromagnetic transition at ∼75 K and a small average effective magnetic moment (1.56 μB/Mn for H ∥ b and 1.37 μB/Mn for H ⊥ b) of Mn from Curie-Weiss fits above 150 K. Specific heat measurements reveal an electronic specific heat coefficient γ of 6.5(2) mJ K-2(mol-Mn)-1 and a small magnetic entropy change Δ Smag ≈ 1.6 J K-1 (mol-Mn)-1 across the antiferromagnetic transition. In contrast to a metallic resistivity along the column, the resistivity perpendicular to the column shows a change from a semiconducting behavior at high temperatures to a metallic one at low temperatures, indicating an incoherent-to-coherent crossover of the intercolumn tunneling of electrons.

中文翻译：

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独特的 [Mn6Bi5]– KMn6Bi5 中的纳米线：一种准一维反铁磁金属

我们报告了一种新的准一维化合物 KMn6Bi5，由平行纳米线组成，在单斜空间群 C2/m 中结晶，a = 22.994(2) Å，b = 4.6128(3) Å，c = 13.3830(13) Å 和 β = 124.578(6)°。纳米线是无限的[Mn6Bi5]-柱，每个柱由作为包层的Bi原子纳米管和位于纳米管中心轴的Mn原子纳米棒组成。Bi 包层内的 Mn 原子纳米棒通过 Mn-Mn 键合稳定，并由 Mn13 的扭曲的 Mn 中心簇二十面体定义，它们沿 b 轴共享它们的顶点。[Mn6Bi5]- 纳米线与弱的内部纳米线 Bi-Bi 键相连，并与 K+ 离子电荷平衡。[Mn6Bi5]-纳米线通过高分辨率透射电子显微镜和扫描透射电子显微镜直接成像。磁化率研究表明，Curie-Weiss 的 Mn 具有一维特性，在 75 K 处具有反铁磁转变，并且具有较小的平均有效磁矩（H ∥ b 为 1.56 μB/Mn，H ⊥ b 为 1.37 μB/Mn）符合上述要求150 K. 比热测量显示电子比热系数 γ 为 6.5(2) mJ K-2(mol-Mn)-1 和小的磁熵变 Δ Smag ≈ 1.6 J K-1 (mol-Mn)-1跨越反铁磁跃迁。与沿柱的金属电阻率相反，垂直于柱的电阻率显示出从高温下的半导体行为到低温下的金属行为的变化，表明电子的柱间隧穿的非相干到相干交叉。